Meet The Snail With A Shell Built Of Iron

Science has discovered lots of animals who had evolved to defend themselves against people, like elephants being born without tusks to not attract the attention of poachers and mice that are resistant to poison. But one fairly recent discovery at the bottom of the Indian Ocean revealed an animal that seems to have taken its cue from humans to defend itself from natural predators.

Wired reported in 2015 on the scaly-foot snail, an ocean mollusk that lives around hydrothermal vents at the bottom of the sea and has had enough of its predators' crap, so it makes its shell and its namesake scales out of iron. Iron sulfide, to be exact. Its foot, the part that sticks out of its shell with which it slithers along the ocean floor, is covered in small, protective iron scales, kind of like chain mail under armor. You could even catch one with a magnet. The snail uses a special type of bacteria to produce this super hard shield, but the bacteria help the scaly-foot snail protect itself from more than just crabs and other snails that would like to make a meal out of it.

Funnily enough, scientists haven't been able to figure out exactly why this particular species of scaly-foot snail creates an iron shell. "It's very strange because a lot of snails must have the same kinds of predators," said biologist Shana Goffredi. "So I don't think there's anything special about the predatory challenges on them, but still it looks like they have really beefed up their shells for some reason."

The answer may not lie with a predatory threat, but rather with an environmental one. The hydrothermal vents these tough little guys call home spit out a pretty toxic amount of sulfides. The bacteria in and on their bodies actually turn those sulfides into the iron sulfide used in their super hard shells and scales. "I think that the microbes play a role in changing the nature of that compound by making it less poisonous," said Goffredi. So the general message to all the other mollusks and crustaceans scuttling across the ocean floor is to not mess with this slow but tough little badass with its armor of iron and poisons.