The name oyster is used for a number of different groups of mollusks which grow for the most part in marine or brackish water. Inside a usually highly-calcified shell is a soft body. The gills filter plankton from the water. Strong adductor muscles are used to hold the shell closed.
Oysters are highly prized as food, both raw and cooked, and have a reputation as an aphrodisiac due to the high content of zinc they contain.