(da Costa, 1778)
Description (shell):
Shell conical or turban-shaped, with deep sutures; solid, smooth, and glossy. Last whorl approximately two-thirds of shell length; aperture pear-shaped with shallow umbilical groove.
Size:
Up to 9 mm.
Colour:
Cream or white with irregular overlay of red or purple streaks and blotches; streaks often produce a flowing zigzag pattern. Columella, inner lip, and operculum milk-white. Specimens lacking a coloured overlay occasionally found.
Animal:
Cephalic tentacles long, slender, papillate; neck lobes comb-like with 11-14 papillate processes. Foot narrow, smooth, with double edge anteriorly and laterally; three pairs of papillate epipodial tentacles. Operculum calcareous, markedly convex in profile. The only British prosobranch with such an operculum.
Habitat:
On rocky shores near LWST and sublittorally to 35 m; intertidally most abundant on tufted red algae such as Lomentaria , Laurencia and Chondrus .
Distribution:
A southern species extending from the Mediterranean to the North Sea; rare in the North (Distr. T. picta).