Periwinkle, << PEHR uh `wihng` kuhl, >> is the common name for a group of marine snails. Periwinkles have a thick, rounded shell that is normally dark in color. They usually cling to rocks that lie in shallow waters or on seashores. Periwinkles feed on tiny plants and on simple plantlike organisms called algae. One well-known periwinkle is the common periwinkle. It grows up to 11/2 inches (4 centimeters) long and lives in northern Europe and the Atlantic coast of North America. Many Europeans eat this periwinkle.
