An edible aquatic snail (family Patellidae) with gills and a conical (patelliform) shell about 6 cm across that inhabits the intertidal zone along the coasts of Western Europe. It grazes algae using a radula with 1920 teeth made from the strongest natural material known, but when wave action threatens to carry it away the limpet uses suction from its muscular foot, combined with an adhesive it secretes, to grip the substrate very firmly (like a limpet). The name ‘limpet’ is also given to several unrelated gastropods with shells that are not coiled.