Naked hermit crab.

Poor little hermit crab.  He lost his shell.  A12 rescued this little guy from having his shell stolen by one of the other hermits in the aquarium.

Hermit crabs come out of their shells to molt and then they go back in unless one of the other crabs decide they want the molting crab's shell or one of the other crabs pinch the molting crab's abdomen which usually means they die.
 
Hermit crabs are not particularly attractive but without their shells, they are really ugly!