If Marvel Comics needs a character to star in yet another TV show, here’s a suggestion: Iron Snail. It would be protected from villains by an iron shell, and by iron plates around its “squishy” bits.
Nature has already created the prototype for Iron Snail: an inch-long snail found around hydrothermal vents in the Indian Ocean. It’s called the scaly-foot snail for the armor that covers its foot -- the fleshy part that extends out of the shell.
Scaly-foot was discovered in 2001, around a single vent about a mile and a half deep. The vent squirts out hot water that’s percolated through cracks below the ocean floor, picking up dissolved minerals.
The snail absorbs some of those minerals, including iron sulfide and pyrite -- fool’s gold. The minerals are the raw ingredients for its shell and the scales on its foot.
The shell has three layers. The inner layer is made of a brittle mineral, the middle layer consists of spongy organic material, and the outer layer contains iron sulfide. When a crab tries to crack the shell with its claws, that three-layer setup absorbs the energy, keeping the snail safe. If the outer layer does crack, it does so only at small, localized points, so the crack doesn’t spread.
The armor plates on the foot also contain iron sulfide. The plates may protect the snail not only from crabs, but from another snail, which injects venom into exposed tissues. That may allow the scaly-foot snail to hang on to a good feeding spot -- safe and snug inside its armor plating.