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11 Unusually Shaped Coins

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Sure, state quarters and presidential dollar coins may be fun. But for a truly unique coin, you need to think outside the box—or the circle, as it were—and come up with a truly original shape. Here are 11 coins with shapes that just might not work in a vending machine.

1. Baseball

In honor of the National Baseball Hall of Fame's 75th anniversary next year, the U.S. Mint announced that it would produce special $5 gold, $1 silver, and half-dollar coins. The twist? They'll be convex, to more closely resemble baseballs. The Mint is running a contest for the design of the concave side—the reverse will feature an anniversary logo for the Hall of Fame. While it's the first time the Mint is venturing into convex coins (and actually it will require an act of Congress to change a law that requires a certain diameter for gold and silver coins), other countries have tried it out. France debuted one in 2009 for the International Year of Astronomy, and Australia made one last year featuring the Southern Cross constellation (above).

2. Australia

The Perth Mint has been working on an unusual series of coins to honor Australia—they're all shaped like the country itself. So far three silver coins have been produced in the series, featuring a kookaburra, an emu, and a kangaroo against backgrounds of iconic Australian landscapes. 

3. Pyramid

To celebrate a worldwide tour of treasures recovered from Tutankhamun's Tomb, the Isle of Man produced special coins shaped as—what else?—a pyramid. The world's first pyramid-shaped coin (triangular, actually) was legal tender on the island, but was designed mainly for collectors. One side featured a drawing of King Tut taken from the tomb itself, with real sand recovered from the entrance of the tomb used to fill in the sun. The other side featured Queen Elizabeth.

4. Guitar

In 2004, Somalia celebrated the 50th anniversary of rock & roll with a limited-edition series of guitar-shaped coins, showing off different popular styles. They included the Gibson Flying V and a pink star guitar, like the one used by Gary Glitter. Based on the popularity of the coins, Somalia issued another set in 2012, this time with Jimmy Page's double-necked guitar and a rectangular one like Bo Diddley played. In the grips of Civil War for years, the Somalian government actually does not distribute currency, so these coins are mostly for collectors. But they've launched a whole series of bizarre shapes, including…

5. Motorcycle


6. Sportscar

And sportscars. You should also check out the rare 3D coin set and an animal series.

7. A Jigsaw Flag

Poland and Ukraine jointly hosted the Euro 2012 football tournament, and in the spirit of cooperation, they released rare bi-national coins. One set had a traditional coin broken into two pieces, one with the value of 10 Polish zloty and the other 10 Ukranian hryvnia. But those had nothing on the special Polish jigsaw coins that, when joined together, formed a flag shape. On one side of the completed coin is the UEFA trophy, on the other a sketch of four football players. Each piece was worth 10 zloty, roughly $2.80 at the time, and represented the four Polish cities that were hosting games in the tournament.

8. Heart

The Pacific island of Palau has tried to appeal to coin collectors with a whole series of unique coins, featuring holograms, gems, and even freshwater pearls. But perhaps their most unusual is a set of heart-shaped coins. A 2009 minting featured a pair of angels, while the 2012 run showed a heart with wings and the slogan "My heart flies for you."

9. Valencia Cathedral

It's unclear why the Cook Islands chose to issue a coin in tribute to Pope Benedict XVI's 2006 trip to Valencia Cathedral in Spain. But the resulting gold-on-silver coin is quite elaborate. It's shaped like the cathedral itself, supposedly the site of the Holy Grail. And where there would normally be a stained glass window, the coin instead features small crystals.

10. Europe

The Republic of Nauru, a South Pacific island also known as Pleasant Island, wanted to honor the 2002 formation of the European Union with its own commemorative coin. Naturally, the $10 silver coin they minted took the shape of all of the founding nations of the E.U.

11. The Bermuda Triangle

Not shying away from its notorious legacy, Bermuda embraced the legend of the Bermuda Triangle with a series of triangular coins, the first coming in 1970. The coins are prized among collectors and feature images of ships sailing in the Atlantic. One 1997 release even displayed the wreckage of the Sea Venture, a 17th-century English ship that crashed into the reefs off of Bermuda.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Name the Author Based on the Character
May 23, 2017
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