They're actually in rocks. Some of the larger life forms found in the deep ocean are no less exotic, including the dumbo octopus, so-called because of its huge, earlike fins. Giant tube worms grow to lengths of several feet and look like they belong on another planet. Much smaller worms the color of red spandex live inside mussels. They look like they were stamped out of a rubber mold.
Crabs are among the most common creatures found along the East Pacific Rise.
Most creatures that live on the sea floor are so adapted to life there that they cannot survive a trip to the surface almost two miles above. The pressure change is so great that these creatures literally explode. It happens to sea-floor bacteria and even rocks, if gas is trapped inside them. Not so the crabs. You can bring the crabs up to the surface.