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Jellyfish aren't fish, and they aren't made of jelly. They look like a blob of jelly when they are out of the ocean, and most species can give you a nasty sting. But in their natural habitat, they are a work of nature's art.

The moon jellyfish is common to shorelines around the world, and often seen washed up on the beach, where it resembles nothing more than a transparent disc. It has short nonstinging tentacles and relies on ocean currents for movement. Here are some recipes, in case you have some fresh moon jellyfish.

Giant jellyfish can grow up to 6.5 feet wide and weigh 450 pounds! They're edible, too.

More jellies, after the jump.

The crystal jelly is a bioluminescent jellyfish. The transparent jellyfish produces green flashes of light chemically due to the green fluorescent protein that scientists use to study gene splicing. These experiments have led to the development of other glowing animals.

The Portuguese Man O'War may be the jellyfish you are most familiar with, but it's not a jellyfish at all! It is actually a colony of specialized invertebrates that cling together to form one eating and reproductive being. The Man O'War floats on the surface of the ocean by filling its bladder with air. The tentacles hang down an average of three feet (but can reach 33 feet), and its sting is very painful and sometimes deadly to humans.

The fried egg jellyfish is native to the Mediteranian Sea and can grow up to 35cm wide. Most jellies depend on ocean currents for movement, but this one can swim on its own by flapping its dome. You can see it swim in this video.

There are many species of box jellyfish native to Australia, the Philippines, and other tropical areas. Some are not dangerous to humans, but one species, Chironex fleckeri, is the world's most venomous animal. The sting from this particular species can cause death in minutes! If stung by a box jellyfish, apply vinegar before removing the tentacles, or it will inject more venom. That's why Australians take vinegar along when swimming at some beaches during jellyfish season.

Jellyfish Lake on the island of Palau is a popular tourist destination. The lake was once connected to the sea, but became isolated by a reef. The jellies that were trapped in the lake thrived due to few predators. They have stinging tentacles, but they are so small that swimmers rarely feel any effects. Watch a video of the lake.

Jellyfish in motion, from National Geographic.

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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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