Untangling the Secrets of Sea Silk, the Ancient Mediterranean’s Elusive Luxury Textile

In the famous Greek myth, the hero Jason and his band of Argonauts seek a precious fleece, allegedly woven from the wool of a golden ram, to exchange for the throne of Thessaly. Around the same era, stories told of the biblical King Solomon describe him wearing a lightweight tunic that shimmered when he stepped into the sunlight. The New Testament repeatedly describes angels as being clothed in "pure and shining linen,” and the apostle Luke as wearing “shining garments.” But was this all just metaphorical holy light—or something real and reproducible? 

As far as anyone knows, there's never been a sheep whose wool gleamed golden. However, many theories have been concocted to explain the existence of a sparkling gold fabric long before the invention of lamé. It’s just a symbol, most say—of wealth, kingship, authority, and so on. 

But these stories also share a possible interpretation that’s based in reality: They may be referring to byssus.

Also known as sea silk, byssus is an ancient textile woven from the beard of various clams, and which appears dark brown until placed under direct light, when it glitters like gold. Although it can be made from a few different mollusks, the beard of the noble pen shell, Pinna nobilis, has historically been the preferred source. Pen shells are quite large as clams go, growing up to 4 feet in length, and produce thin but very strong filaments—solidified saliva, really—that anchor the mollusks to the floor of the sea. With strands about half the circumference of a human hair, the silken beard of P. nobilis is ideal for weaving, as it's far less coarse than that of its cousins in the pinnidae family. 

The threads of the fabric’s history are difficult to trace, beginning with the fact that the word byssus itself once referred to any precious textile. The Old Testament reportedly includes 45 mentions, but some of them, judging from the context, almost certainly refer to linen, cotton, or regular silk. The same is true for the cloth that Egyptians used to wrap mummies, which scholars have translated as “byssus." But it’s hard to be sure which byssus they’re talking about: sea silk, or another precious textile? The silken filaments that compose the pen shell’s beard are also called byssus, adding to the confusion.

And fictions have thrived around byssus: In 945, the Book of Tang (Tángshū), a historical work about the imperial Tang dynasty of China, described a golden textile called byssus as being woven “from the hair of the sea-sheep,” whatever that might have been. Estakhri, a 9th-century Persian geographer, writes similarly of an animal that runs into the sea and rubs itself against certain stones, whereupon it produces "a kind of wool of silken hue and golden color."

Much later, Jules Verne spoke of it in Twenty Thousand Leagues Under the Sea. In the original French version, he describes the crew of the Nautilus being dressed in byssus and detailed its aquatic origins. However, “byssus” was called “seashell tissue" or "fan mussel fabric" in English translations, which caused some readers to believe the material was dreamt up expressly for science fiction. 

The real, clam-made byssus was highly prized by the ancient Greeks and Mesopotamians, among other cultures, for not only its glittery, color-shifting properties but also for its combination of daintiness and warmth. Stockings and gloves were popular uses for sea silk; a pair of byssus gloves were reported to be so extraordinarily light they would fit folded inside of a walnut's shell, and a pair of stockings inside a snuff box. 

Women spinning bysso, from a display in Sardinia. Image credit: Sicco2007, Flickr // CC BY-NC-ND 2.0

Byssus fell out of fashion for a few centuries, although it enjoyed a short renaissance in the 1800s among the wealthy. But aside from museum and gallery collections exhibiting vintage pieces, it’s nearly nonexistent today, and for good reason. P. nobilis is currently endangered—a victim of not just overfishing and trawling in the Mediterranean but also of pollution, to which it's highly susceptible. These factors make the harvesting of the byssus all the more difficult—and the cloth itself perhaps even more expensive than it was in ancient times.

However, Italian weaver Chiara Vigo, who says she has developed a method of harvesting the silken fibers from the pen shell without killing the creature, has been granted special clearance to dive for them in her hometown of Sant'Antioco, Sardinia, while accompanied by members of the Italian Coast Guard. Vigo’s family has been weaving byssus for centuries. She learned the trade from her grandmother—although it should perhaps be called a “trade” only loosely, since she's sworn to never sell the cloth (further adding to its scarcity). Vigo believes the cloth is sacred, calling it “the soul of the sea,” and claims to have never earned a cent (or lira) from her skill.

As the BBC notes, Vigo also believes that a gift of byssus brings good fortune to families, so she provides her service to those who appear at her studio in person. She gives byssus-embroidered christening dresses to babies, byssus bracelets to pregnant women (or those who aspire to be), and byssus rings to little girls (to bring back to Vigo when they're grown and engaged, whereupon she’ll make them a byssus doily for their marriage bed).

Rumor has it that a few elderly women on the Italian mainland still know how to weave byssus, but Vigo is the only known living master. She’s only person who can make it shine, using a special solution, and who can dye it in the traditional way. She’s also said to be the only person who is legally cleared to harvest it. And Vigo holds a secret, to boot: She’s one of the few living people who know where exactly the field of pen shells is located in the waters surrounding Sant’Antioco.

Whatever the truth behind byssus’s complicated backstory, the good news is that for now, sea silk is still quietly being woven in an ancient village on a tiny island just off of a larger island in the Mediterranean—and that Chiara Vigo is willing to share her knowledge. In addition to spending a few hours in the evenings teaching students how to weave byssus, she has also taught her daughter the craft, vowing that she’ll one day take over the family tradition. Hopefully, in an era where glitter is everywhere but traditional materials are scarce, the fabric will continue to survive, and as more than a myth. 

14 Bold Facts About Bald Eagles

Bald eagles are powerful symbols of America—but there’s a whole lot more to these quirky birds.


A young bald eagle with a brown head on a beach.

So obviously adult bald eagles aren't really bald, either—their heads have bright white plumage that contrasts with their dark body feathers, giving them a "bald" look. But young bald eagles have mostly brown heads. In fact, for the first four or five years of their lives, they move through a complicated series of different plumage patterns; in their second year, for instance, they have white bellies.


A red-tailed hawk.
A red-tailed hawk's screech is usually dubbed over the bald eagle's weaker scream.

It's a scene you’ve probably seen countless times in movies and on TV: an eagle flies overhead and emits a rough, piercing scream. It's a classic symbol of wilderness and adventure. The only problem? Bald eagles don't make that sound.

Instead, they emit a sort of high-pitched giggle or a weak scream. These noises are so unimpressive that Hollywood sound editors often dub over bald eagle calls with far more impressive sounds: the piercing, earthy screams of a smaller bird, the red-tailed hawk. If you were a fan of The Colbert Report, you might remember the show's iconic CGI eagle from the opener—it, too, is making that red-tailed hawk cry. Listen for yourself and decide who sounds more impressive.


Two bald eagles guard their prey against two magpies on a snowy field.

Picture a majestic bald eagle swooping low over a lake and catching a fish in its powerful claws. Yes, bald eagles eat a lot of fish—but they don't always catch it themselves. They've perfected the art of stealing fish from other birds such as ospreys, chasing them down until they drop their prey.

Bald eagles will also snack on gulls, ducks, rabbits, crabs, amphibians, and more. They'll scavenge in dumpsters, feed on waste from fish processing plants, and even gorge on carrion (dead, decaying animals).


Two bald eagles perched on a tree.

Trash and carrion aside, they're pretty romantic animals. Bald eagles tend to pair up for life, and they share parenting duties: the male and the female take turns incubating the eggs, and they both feed their young.


Two bald eagles sitting on a rock.

Those romantic partnerships are even more impressive because bald eagles can survive for decades. In 2015, a wild eagle in Henrietta, New York, died at the record age of 38. Considering that these birds pair up at 4 or 5 years of age, that's a lot of Valentine's Days.


Two bald eagles in their large nest.

Bald eagles build enormous nests high in the treetops. The male and female work on the nest together, and this quality time helps them cement their lifelong bond. Their cozy nurseries consist of a framework of sticks lined with softer stuff such as grass and feathers. If the nest serves them well during the breeding season, they'll keep using it year after year. And, like all homeowners, they can't resist the thought of renovating and adding to their abode. Every year, they'll spruce it up with a whopping foot or two of new material.

On average, bald eagle nests are 2-4 feet deep and 4-5 feet wide. But one pair of eagles near St. Petersburg, Florida, earned the Guinness World Record for largest bird’s nest: 20 feet deep and 9.5 feet wide. The nest weighed over two tons.


Two bald eagles in their large nest.

In many animal species, males are (on average) larger than females. Male gorillas, for example, dwarf their female counterparts. But for most birds of prey, it's the opposite. Male bald eagles weight about 25 percent less than females.

Scientists aren't sure why there's such a size difference. One reason might be the way they divide up their nesting duties. Females take the lead in arranging the nesting material, so being bigger might help them take charge. Also, they spend longer incubating the eggs than males, so their size could intimidate would-be egg thieves.

If you're trying to tell male and female eagles apart, this size difference may help you—especially since both sexes have the same plumage patterns.


A bald eagle flies across the water.

People often get excited about a big soaring bird and yell "It's an eagle!” just before it swoops closer and … oops, it's a vulture. Here's a handy identification tip. Bald eagles usually soar with their wings almost flat. On the other hand, the turkey vulture—another dark, soaring bird—holds its wings up in a shallow V shape called a dihedral. A lot of large hawks also soar with slightly raised wings.


Baby eagle chicks in a nest.

Before European settlers arrived, bald eagles were abundant across the U.S. But with settlement came habitat destruction, and the settlers viewed the eagles as competition for game and as a threat to livestock. So many eagles were killed that in 1940 Congress passed an act to protect the birds.

Unfortunately, another threat rose up at about that time. Starting after World War II, farmers and public health officials used an insecticide called DDT. The chemical worked well to eradicate mosquitos and agricultural pests—but as it traveled up the food chain, it began to heavily affect birds of prey. DDT made eagle eggshells too thin and caused the eggs to break. A 1963 survey found just 471 bald eagle pairs in the lower 48 states.

DDT was banned in the early 1970s, and conservationists began to breed bald eagles in captivity and reintroduce them in places across America. Luckily, this species made a spectacular recovery. Now the lower 48 states boast over 9700 nesting pairs.


An African fish eagle flies over the water.
The African fish eagle is a relative of the North American bald eagle.

You've probably heard of America's other eagle: the golden eagle. This bird lives throughout much of the northern hemisphere. But the bald eagle is only found in North America. It lives across much of Canada and the U.S., as well as northern parts of Mexico.

Though it may be North American, the bald eagle has seven close relatives that are found throughout the world. They all belong to the genus Haliaeetus, which comes—pretty unimaginatively—from the Latin words for "sea" and "eagle." One relative, the African fish eagle, is a powerful symbol in its own right. It represents several countries; for example, it's the national symbol of Zambia, and graces the South Sudanese, Malawian, and Namibian coats of arms.


A bald eagle carries a fish off in its talons.

It seems too weird to be true: While flying, bald eagles sometimes grab each other's feet and spin while plummeting to the Earth. Scientists aren't sure why they do this—perhaps it's a courtship ritual or a territorial battle. Usually, the pair will separate before hitting the ground (as seen in this remarkable set of photographs). But sometimes they hold tight and don't let go. These two male bald eagles locked talons and hit the ground with their feet still connected. One subsequently escaped and the other was treated for talon wounds.


Close-up of a bald eagle's face.

What if you could close your eyes and still see? Besides the usual pair of eyelids, bald eagles have a see-through eyelid called a nictitating membrane. They can close this membrane to protect their eyes while their main eyelids remain open. The membrane also helps moisten and clean their eyes.

Eagles also have sharper vision than people, and their field of vision is wider. Plus, they can see ultraviolet light. Both of those things mean the expression "eagle eye" is spot-on.


A bald eagle sits in a snowy tree.

If you're a bald eagle that nests in northern Canada, you'll probably head south for the winter to avoid the punishing cold. Many eagles fly south for the winter and return north for the summer—as do plenty of other bird species (and retired Canadians). But not all bald eagles migrate. Some of them, including individuals in New England and Canada's Maritime provinces, stick around all year. Whether or not a bird migrates depends on how old it is and how much food is available.


A bald eagle

There are several videos online—like the one above—that show a bald eagle swimming in the sea, rowing itself to shore with its huge wings. Eagles have hollow bones and fluffy down, so they can float pretty well. But why swim instead of soar? Sometimes, an eagle will swoop down and grab an especially weighty fish, then paddle it to shore to eat.

Note that the announcer in the video above says that the eagle's talons are "locked" on a fish that's too heavy to carry. In fact, those lockable talons are an urban legend.

How Bats Protect Rare Books at This Portuguese Library

Visit the Joanina Library at the University of Coimbra in Portugal at night and you might think the building has a bat problem. It's true that common pipistrelle bats live there, occupying the space behind the bookshelves by day and swooping beneath the arched ceilings and in and out of windows once the sun goes down, but they're not a problem. As Smithsonian reports, the bats play a vital role in preserving the institution's manuscripts, so librarians are in no hurry to get rid of them.

The bats that live in the library don't damage the books and, because they're nocturnal, they usually don't bother the human guests. The much bigger danger to the collection is the insect population. Many bug species are known to gnaw on paper, which could be disastrous for the library's rare items that date from before the 19th century. The bats act as a natural form of pest control: At night, they feast on the insects that would otherwise feast on library books.

The Joanina Library is famous for being one of the most architecturally stunning libraries on earth. It was constructed before 1725, but when exactly the bats arrived is unknown. Librarians can say for sure they've been flapping around the halls since at least the 1800s.

Though bats have no reason to go after the materials, there is one threat they pose to the interior: falling feces. Librarians protect against this by covering their 18th-century tables with fabric made from animal skin at night and cleaning the floors of guano every morning.

[h/t Smithsonian]


More from mental floss studios