The eastern oyster, also known as the Atlantic oyster or American oyster, is a species of bivalve mollusk native to the Atlantic coast of North America. The soft body of the oyster is protected by the two hard, calcium carbonate shells that encase it. Oysters are filter feeders, pulling in water and catching and consuming any small plankton and particles of organic matter that it might contain. The filter-feeding action of oysters can significantly clean the waterways in which they live.