(Linné, 1767)
Description (shell):
Broadly oval, about one and a half times long as wide. Shell valves smoothly arched, rather low, with distinct, low keel and pronounced beaks. Sculpture of very regular, fine granulation, becoming slightly coarser towards margins where growth lines may be enhanced. Head valve with eight or nine anterior ventral notches; intermediate valves typically with one indistinct notch laterally (rarely two), articulamentum developed on each side as a gently convex, semi-elliptical plate. Girdle relatively narrow, densely covered with fine rounded granules; fringed with fusiform spines (L. cinerea-drawing).
Size:
Up to 24 mm long.
Colour:
Colour variable: red, brown, yellow to green, in patches and bands.
Habitat:
Middle to lower shore, and sublittoral.
Distribution:
Widespread and common (Distr. L. cinerea).