Limpet, a water-dwelling snail. Most kinds live in the sea on the shoreline. The shell of the sea limpet is usually a flattened cone one to two inches (2.5 to 5 cm) in length. When the tide is out the limpet clings to a rock with its powerful foot, which acts like a suction cup. At high water the limpet moves about and feeds on algae, which it rasps away from rocks with its filelike tongue. As the tide goes out, it returns to its original rock, where it eventually wears a smooth depression the size of its shell. The limpet spends a short period of its life as a free-swimming larva before settling on its rock.
Limpets are used for bait. Some, including the common European limpet, are used for food.
Limpets belong to the class Gastropoda of the phylum Mollusca. The common European limpet is Patella vulgata. Other species include the whitecap limpet, Acmaea mitra, and the rough keyhole limpet, Diodora aspera, both found on the Pacific coast of North America; and the New England limpet, A. testudinalis.Limpets are water-dwelling snails with flattened cone-like shells.