(Gmelin, 1791)
Description (shell):
Broadly oval, about one and a half times long as wide. With distinct keel and small posterior beaks. Sculpture of fine granules, becoming coarser towards margins and accentuating growth lines. Edges of plates finely denticulate; articulamentum semi-elliptical, with smooth edge. Girdle relatively narrow, covered with overlapping, elongate rectangular scales, each with distinct longitudinal striations; fringed with delicate marginal spines (L. asellus-detail).
Size:
Up to 18 mm, rarely larger.
Colour:
Shell valves off-white or yellow, often with black or brownish organic incrustations.
Habitat:
Lower shore and sublittoral.
Distribution:
Widespread and common (Distr. L. asellus).