The Mysterious Bronze Objects That Have Baffled Archaeologists for Centuries

The Roman dodecahedron Brian Campbell found in East London
The Roman dodecahedron Brian Campbell found in East London
Brian Campbell

One August day in 1987, Brian Campbell was refilling the hole left by a tree stump in his yard in Romford, East London, when his shovel struck something metal. He leaned down and pulled the object from the soil, wondering at its strange shape. The object was small—smaller than a tennis ball—and caked with heavy clay. “My first impressions," Campbell tells Mental Floss, "were it was beautifully and skillfully made … probably by a blacksmith as a measuring tool of sorts.”

Campbell placed the artifact on his kitchen windowsill, where it sat for the next 10 or so years. Then, he visited the Roman fort and archaeological park in Saalburg, Germany—and there, in a glass display case, was an almost identical object. He realized that his garden surprise was a Roman dodecahedron: a 12-sided metal mystery that has baffled archaeologists for centuries. Although dozens, and perhaps hundreds, of explanations have been offered to account for the dodecahedrons, no one is certain just what they were used for.


A dodecahedron at the Saalburg Roman Fort Archaeological Park
A dodecahedron at the Saalburg Roman Fort Archaeological Park
Rüdiger Schwartz/Saalburg Roman Fort Archaeological Park

The first Roman dodecahedron to intrigue archaeologists was found almost 300 years ago, buried in a field in the English countryside along with some ancient coins. "A piece of mixed metal, or ancient brass, consisting of 12 equal sides," read the description of the egg-sized object when it was presented to the Society of Antiquaries in London in 1739. The 12 faces had "an equal number of perforations within them, all of unequal diameters, but opposite to one another … every faceing had a knobb or little ball fixed to it." The antiquarians were flummoxed by the finely crafted metal shell, and what its purpose may have been.

The 1739 dodecahedron was far from the last discovery of its kind. More than 100 similar objects have since been found at dozens of sites across northern Europe dating to around the 1st to 5th centuries CE. Ranging in size from about a golf ball to a bit larger than a baseball, each one has 12 equally sized faces, and each face has a hole of varying diameter. The objects themselves are all hollow.

By the mid-19th century, as more were found, the objects became known to archaeologists as dodecahedrons, from the Greek for “12 faces.” They're on display today in dozens of museums and archaeological collections throughout Europe, although given how little is known about them, their explanatory labels tend to be brief.

What's more, they have no paper trail. Historians have found no written documentation of the dodecahedrons in any historical sources. That void has encouraged dozens of competing, and sometimes colorful, theories about their purpose, from military banner ornaments to candleholders to props used in magic spells. The obvious craftsmanship that went into them—at a time when metal objects were expensive and difficult to make—has prompted many researchers to argue they were valuable, an idea that's supported by the fact that several have been found stashed away with Roman-era coins. But that still doesn't explain why they were made.


A Roman cavalry charge, a relief from the Arch of Constantine in Rome, circa 315 CE
A Roman cavalry charge, from the Arch of Constantine in Rome, circa 315 CE
Hulton Archive/Getty Images

In the 19th century, some antiquarians favored the theory that the dodecahedrons were a type of weapon—perhaps the head of a mace (a type of club with a heavy head), or a metal bullet for a hand-held sling. But as other scholars later pointed out, even the largest of the dodecahedrons are too light to inflict much damage. Moreover, Roman soldiers usually fired solid lead balls from their slings—nothing that looked like the intricate, and hollow, dodecahedrons.

Yet weapons aren't the only items useful in a war. Amelia Sparavigna, a physicist at Italy’s Politecnico di Torino, thinks the dodecahedrons were used by the Roman military as a type of rangefinder. In research published on the online repository arXiv in 2012, Sparavigna argued that they could have been used to calculate the distance to an object of known size (such as a military banner or an artillery weapon) by looking through pairs of the dodecahedrons' differently sized holes, until the object and the edges of the two circles in the dodecahedron aligned. Theoretically, only one set of holes for a given distance would line up, according to Sparavigna.

The theory is strengthened by the fact that several of the dodecahedrons have been found at Roman military sites. Sparavigna tells Mental Floss that “the small little studs [on the outside allow for] a good grip of the object. So an expert soldier could use it in any condition,” while the many pairs of holes allowed them to quickly select between a variety of ranges. “The Roman army needed a rangefinder, and the dodecahedron can be used as a rangefinder,” she explains.

But many modern scholars disagree. Historian Tibor Grüll of the University of Pécs in Hungary, who reviewed the academic literature about the dodecahedrons in 2016, points out that no two Roman dodecahedrons are the same size, and none have any numerals or letters engraved on them—markings you might expect on a mathematical instrument. “In my opinion, the practical function of this object can be excluded because ... none of the items have any inscriptions or signs on [them],” Grüll tells Mental Floss.

He points to the distribution of the objects as an important clue. They have been found across a northwestern swath of the former Roman Empire from Hungary to northern England, but not in other Roman territories such as Italy, Spain, North Africa, or the Middle East. That lack works against the idea that the objects were military devices. "If it was a tool for ranging artillery," Grull says, "why does it not appear all over the empire in a military context?"


Perhaps the dodecahedrons were used for play, not war. Some scholars have suggested they may have been part of a child’s toy, like the French cup-and-ball game known as bilboquet, which dates from the Middle Ages. Their shape also invites comparisons to the dice used for gambling, a common pastime in the Roman era. But most Roman dice were six-sided, smaller, and carved from solid wood, stone, or ivory. Plus, the differently sized holes on each face of the dodecahedrons makes them useless as dice: One side is always heavier than the other, so they always fall the same way.

Many scholars have suggested that the items had a special cultural significance, and perhaps even a religious function, for the peoples in the formerly Gallic regions of northern Europe. The 1939 discovery of a well-preserved bronze dodecahedron in Krefeld, near Germany’s border with the Netherlands, lends credence to this idea. The object was found in the 4th-century CE grave of a wealthy woman, along with the remains of a bone staff. According to an essay from the Gallo-Roman Museum at Tongeren in Belgium, the dodecahedron was likely mounted on the staff like a kind of scepter head, and "probably ascribed with magical powers, bestowing religious power and prestige on its owner."

Or perhaps they had a different kind of cultural significance. Divination or fortune-telling was popular throughout the Roman empire, and the 12 sides of the dodecahedrons could suggest a link to the astrological zodiac. Others have suggested a link to Plato, who said that the dodecahedron was the shape “used for embroidering the constellations on the whole heaven.” (It's not quite clear exactly what Plato was talking about.)

Rüdiger Schwarz, an archaeologist at the Saalburg Roman Archaeological Park near Frankfurt in Germany—where Campbell first identified the curious object he'd found—explains that any discussion of the cultural significance of the objects is purely speculative. “We have no sources from antiquity which give an explanation of the function or the meaning of these objects,” Schwarz says. “Any of these theories may be true, but can neither be proved right or wrong.”

Schwarz points to another theory: The dodecahedrons may have been a type of “masterpiece” to show off a craftsman's metalworking abilities. This might be why they rarely show any signs of wear. “In this respect, the technical function of the dodecahedron is not the crucial point. It is the quality and accuracy of the work piece that is astonishing,” he tells Mental Floss. “One could imagine that a Roman bronze caster had to show his ability by manufacturing a dodecahedron in order to achieve a certain status.”


Of course, the internet loves an ancient mystery, and ideas about the purpose of the Roman dodecahedrons have flourished there. The work of Dutch researcher G.M.C. Wagemans, detailed at, proposes that the objects were astronomical instruments used to calculate agriculturally important dates in the spring and fall by measuring the angle of sunlight through the different pairs of holes. Other internet researchers, perhaps less seriously, have used 3D-printed models of the Roman dodecahedrons for knitting experiments, and suggested that the true purpose of the objects was to create differently sized fingers for Roman woolen gloves.

Campbell has taken his artifact to several museums in London, but beyond confirming what it is, they could provide no further clues about its particular origin or purpose. "Many [is] the time I have handled it wondering as to its exact use," he says.

While Campbell has no clear idea what the Romans were doing with the dodecahedron—which he now keeps in a display cabinet in his house—he does propose how it might have come to be in his garden: by being left behind by soldiers traveling between London and the early Roman provincial capital of Camulodunum, now Colchester in Essex. Romford was at that time a river crossing and the probable site of a fortified posting station used by Roman troops for changing horses and resting in safety.

“Two thousand years ago, I believe this area was forested and the River Rom's flood plain was much wider than today,” Campbell says. “I often form a picture in my head of 100 or so Roman soldiers in full uniform bedding down in the area, now the bottom of my garden.”

Roman dodecahedrons are still being found today. Recent examples have been unearthed by metal-detectorists in the north of England, and by archaeologists excavating a late-Roman rubbish pit in the north of France [PDF]. It's likely more will be found in the future.

But unless someone also finds an instruction manual—and after more than 1500 years, that seems doubtful—the Roman dodecahedrons will continue to baffle, and fascinate, for many years to come.

How Thomas Jefferson's Obsession With Mastodons Partly Fueled the Lewis and Clark Expedition

James St. John, Flickr // CC BY 2.0
James St. John, Flickr // CC BY 2.0

By the 1800s, American mastodons—prehistoric relatives of the elephant—had been extinct for roughly 10,000 years. Thomas Jefferson didn’t know that, though. The Founding Father dreamed of finding a living, breathing mastodon in America, and this lofty goal ended up being a motivating force throughout much of his life. Even during the Revolutionary War, and even when he ran for the highest office in the land, he had mastodons on the mind. Jefferson was convinced that the hairy beasts still roamed the continent, probably somewhere on the uncharted western frontier, and he was determined to find them—or, at the very least, enlist a couple of intrepid explorers by the names of Meriwether Lewis and William Clark to do the hunting on his behalf.

The Corps of Discovery departed from St. Louis on May 14, 1804 and headed into the great unknown of the Louisiana Purchase in search of an all-water route to the Pacific. The adventurers made many discoveries on the two-and-a-half-year round trip—mapping the geography of the region and logging hundreds of species of flora and fauna unknown to science—but the directive to look for mastodons is a little-known footnote to their famous expedition.

At the start of their trip, Jefferson instructed Lewis and Clark to be on the lookout for “the remains and accounts of any [animal] which may be deemed rare or extinct.” Although he didn’t mention mastodons specifically—at least not in any of the written correspondence on record—the two explorers were all too familiar with Jefferson’s mammoth ambition. “Surely Jefferson still had the M-word in mind, and surely Lewis knew it,” author Robert A. Saindon writes in Explorations Into the World of Lewis and Clark, Volume 2.

Jefferson had long been interested in paleontology, but his mastodon obsession was fueled by a longstanding beef he had with a French naturalist who thought America’s animals and people were puny. Jefferson’s bone-collecting hobby quickly evolved into a mission to assert America’s dominance in the Western world and prove that it was "a land full of big and beautiful things," as journalist Jon Mooallem put it in his book, Wild Ones. Indeed, there are worse ways to become a political and cultural heavyweight than to prove your country is home to a 12,000-pound monster.

A Rivalry Forms

Georges-Louis Leclerc, Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon

François-Hubert Drouais, Wikimedia Commons // Public domain

For much of his adult life, Jefferson was an avid collector of fossils and bones. At various points in time, he owned a bison fossil, elk and moose antlers, giant ground sloth fossils, and naturally, a number of mastodon bones.

Though his original interest may have been purely academic, Jefferson's exposure to the writings of French naturalist Georges-Louis Leclerc, Comte de Buffon fanned the flames of his obsession. Buffon’s “Theory of American Degeneracy,” published in the 1760s, postulated that the people and animals of America were small and weak because the climate (he assumed, without much evidence) was too cold and wet to encourage growth.

Jefferson was furious. He formulated a rebuttal, which partly drew attention to the inconsistencies in Buffon's beliefs about the mastodon. Buffon suggested that the American mastodon was a combination of elephant and hippopotamus bones, but because Jefferson had inspected the bones, he knew that the measurements didn't match those of previously known species. Instead, Jefferson argued that the bones belonged to a different animal entirely. (Although they’re distinct species, woolly mammoths and mastodons were lumped into the same category at the time, and were called one of two names: mammoths or the American incognitum.)

“The skeleton of the mammoth … bespeaks an animal of five or six times the cubic volume of the elephant,” Jefferson wrote. He later scaled back his argument a bit, adding, “But to whatever animal we ascribe these remains, it is certain such a one has existed in America, and that it has been the largest of all terrestrial beings.”

He didn’t just believe that mastodons had existed at one point in time, though—he believed they were still out there somewhere. It wasn’t unusual for thinkers and scientists of Jefferson's era to assume that bones were evidence of a still-living species. After all, dinosaurs had not yet been discovered (though their bones had been found, no one would call them dinosaurs until the early 19th century), and the concept of extinction wasn’t widely accepted or understood. Dominant religious beliefs also reinforced the idea that God’s creations couldn't be destroyed.

For his part, Jefferson believed that animals fell into a natural order, and that removing a link in “nature’s chain” would throw the whole system into disarray. Taking the tone of a philosopher, he once questioned, “It may be asked, why I insert the Mammoth, as if it still existed? I ask in return, why I should omit it, as if it did not exist?”

This position may have been partly fueled by wishful thinking. Jefferson believed that tracking down a living mastodon would be the most satisfying way to stick it to Buffon and say, “I told you so.” (In the meantime, though, he had to settle for a dead moose, which he sent overseas to the Frenchman’s doorstep in Paris to prove that large animals did, in fact, exist in America.)

The Hunt Continues

A painting of The Exhumation of the Mastadon

This 1806 painting by Charles Willson Peale, titled The Exhumation of the Mastadon, shows mastodon bones being excavated from a water-filled pit.

Charles Willson Peale, Wikimedia Commons // Public domain

In late 1781, Jefferson wrote to his buddy George Rogers Clark in the Ohio valley and asked him to fetch some mastodon teeth from a nearby "mastodon boneyard" in northern Kentucky called Big Bone Lick. “Were it possible to get a tooth of each kind, that is to say a foretooth, grinder, &c, it would particularly oblige me,” Jefferson wrote. Clark politely explained that the possibility of Native American attacks made this task impossible, but he was able to procure a thighbone, jaw bone, grinder, and tusk from travelers who had managed to visit the frontier.

However, Jefferson didn’t receive Clark's reply until six months later in August 1782 (because of, you know, the Revolutionary War). Although the war technically didn't end until the following year, peace talks between the two sides were nearing a conclusion, and everybody knew it. With an end to the conflict in sight, Jefferson doubled down on his request for mastodon bones. He wrote to Clark, “A specimen of each of the several species of bones now to be found is to me the most desireable object in Natural History, and there is no expence of package or of safe transportation which I will not gladly reimburse to procure them safely.”

Later, while serving as America’s first Secretary of State, Jefferson supported a proposed Western exploration that would have preceded the Lewis and Clark expedition. Before the expedition was called off, Jefferson had instructed the would-be explorer, French botanist André Michaux, to look for mastodons along the way. He wrote to Michaux in 1793, “Under the head of Animal history, that of the Mammoth is particularly recommended to your enquiries.”

Even when Jefferson turned his attention to national politics and ran for president against incumbent John Adams in 1800, he was still thinking about mastodons. His preoccupations were so widely known that his opponents, the Federalists, called him a “mammoth infidel” in reference to his unusual hobby and supposed secular leanings. As an 1885 article in the Magazine of American History recalled, “When Congress was vainly trying to untangle the difficulties arising from the tie vote between Jefferson and [Aaron] Burr, when every politician at the capital was busy with schemes and counter-schemes, this man, whose political fate was balanced on a razor’s edge, was corresponding with [physician and professor] Dr. [Caspar] Wistar in regard to some bones of the mammoth which he had just procured from Shawangunk, Ulster County.”

Once president, Jefferson used his office to further the field of paleontology. Not long after he was elected, he loaned one of the Navy’s pumps to artist and naturalist Charles Willson Peale, who wanted to extract a pile of freshly unearthed mastodon bones from a water-filled pit. It ultimately became the first fossilized skeleton to ever be assembled in America.

Of course, there is also evidence that Jefferson silently hoped Lewis and Clark would stumble upon a living mastodon during their expedition, which formally kicked off in 1804 and ended in 1806. That, as we now know, was impossible. After their return, Jefferson sent William Clark on a second assignment to collect artifacts from Big Bone Lick. He sent three big boxes of bones back to Jefferson, who got to work unloading and studying them in the East Room of the White House—the same room where John and Abigail Adams once hung their laundry.

Still, something wasn’t quite right, and Jefferson may have known it even then. By 1809, the animal in question had been identified and given the name mastodon, and Jefferson started to reverse some of his previously held opinions. In a letter to William Clark, he conceded that the mastodon was not a carnivore, as he once believed, but an herbivore. "Nature seems not to have provided other food sufficient for him," he wrote, "and the limb of a tree would be no more to him than a bough of cotton tree to a horse."

Accepting the Mastodon’s Fate

Thomas Jefferson
National Archive/Newsmakers

The fact that Lewis and Clark never spotted any giants roaming out West may have helped Jefferson accept the inevitable: Mastodons had gone extinct long ago. Waxing poetic in a letter to John Adams in 1823, Jefferson wrote, “Stars, well known, have disappeared, new ones have come into view, comets, in their incalculable courses, may run foul of suns and planets and require renovation under other laws; certain races of animals are become extinct; and, were there no restoring power, all existences might extinguish successively, one by one, until all should be reduced to a shapeless chaos.”

Although he was unsuccessful in his quest to find a living mastodon, Jefferson made other meaningful contributions to the field of paleontology. The fossils of another mysterious creature he believed to be a lion were later revealed to be that of a giant ground sloth. He named it Megalonyx (Greek for “great claw”), and in 1822, the extinct creature was renamed Megalonyx jeffersonii in Jefferson’s honor.

Nowadays, the ground sloth fossils—and several other items that formed the "cabinet of curiosities" Jefferson displayed at his Monticello estate—are part of The Academy of Natural Science collection at Drexel University. Considering that Jefferson is sometimes called "the founder of North American paleontology,” it would appear he got his revenge against Buffon after all.

A Pair of Dutch World War II Shipwrecks Have Disappeared Off the Coast of Malaysia

jfybel/iStock via Getty Images
jfybel/iStock via Getty Images

For nearly 80 years, two Dutch submarines have been occupying the ocean floor off the coast of Malaysia, with the remains of their crews still inside. They were among dozens of shipwrecks in the same area, all of them casualties of underwater World War II battles. Now, the ships— known as HNLMS O 16 and HNLMS K VII—are gone.

There’s nothing paranormal at work, though. Instead, the ships have vanished as a result of greed. Scavengers in the area have made a profitable pursuit of placing explosives within the wrecks, blowing them into manageable pieces and taking off with the scrap metal using a crane. Copper and bronze materials can also be resold. It’s estimated that about 40 ships in Indonesia, Singapore, and Malaysia have been demolished as a result of such efforts in recent years.

Because the ships are typically considered unmarked graves, the thieves may be committing the crime of desecrating corpses. After several British ships were found ransacked, the UK’s Ministry of Defense urged Indonesia to increase their efforts to protect the ships. The United States has dispatched representatives in Indonesia to guard ships they believe have been targeted by the scavengers.

Marine archaeologists have expressed some puzzlement at the phenomenon, as the scrap can often take weeks to retrieve, is frequently corroded, and would seemingly be cost-prohibitive to steal considering the labor involved. It’s possible that the ships may be targeted for having low-background metals, which are free from radiation because they pre-date atomic bomb testing and can be used in delicate scientific instruments like Geiger counters. In China, scrap metal could bring in about $1.3 million per ship. 

[h/t Live Science]