From Longman Dictionary of Contemporary Englishhermit crabˈhermit ˌcrab noun [countable] HBAa kind of crab that lives in the empty shells of other sea creatures
Examples from the Corpus
hermit crab• Anyone who has tried to remove a hermit crab from its shell will know how tenacious these creatures can be.• A hermit crab carrying a sea anemone around on its shell.• A hermit crab sticks sand and weed on its shell, and all Jay's glitz was camouflage.• But the cowbird and hermit crab can make no such claims.• Suitably sized shells are often in short supply and in some areas this limits the hermit crab population.• Sometimes you can find a Zebra flatworm sharing the snail shell with the hermit crab. 