(Linnaeus, 1758)
Description:
Conical and circular shape with irregular edge. The wall plates are heavily ridged and strong, radii parallel. The orifice is moderately sized, acutely angled at the tergal end, rounded anteriorly. The operculum is raised, tergum with prominent points, scutum with prominent ridges corresponding to growth lines. The tergoscutal flaps are edged yellow, backed by brown stripes, followed by a white stripe. The basis is solid and calcareous.
Size:
Large; up to 25 (30) mm.
Colour:
White or tinged brown.
Habitat:
On rocks, stones and shells; LWST to several hundreds metres deep. Occasionally on ships.
Distribution:
In British Isles on all coasts except Cornwall. Abundant. Elsewhere, Arctic Circle to North and Celtic Seas.