(Linné, 1767)
Description (shell):
Elongate oval, twice as long as broad. Shell valves strongly arched, with a rounded keel and prominent beaks. Sculpture of longitudinal ridges on the keel, laterally with fine, densely packed, oval or rounded granules. Girdles with 18 dense tufts of bristles (up to 1.5 mm long), one on each side at posterior valve boundaries and four in an arc anterior to head valve; surface covered with densely packed, recumbent spines (feeling velvety to touch) and fringed with dense series of longer spines (up to 1 mm).
(A. fascicularis-detail).
Size:
Up to 60 mm long.
Colour:
Variable, marbled with off-white, grey, yellowish or brown.
Habitat:
Lower shore and sublittoral.
Distribution:
Only in the southern North Sea (Distr. A. fascicularis); recorded distribution from north Kent, south and west to Channel Isles, northwards to Anglesey and on west coast of Ireland.