Velutina velutina

(Müller, 1776)

Description (shell):
Shell fragile, semi-transparent, with up to three rapidly expanding, tumid whorls, covered by periostracum; last whorl comprises most of shell; spire low, occasionally in a small depression. Sculpture of fine spiral striae and growth lines, producing reticulate pattern. Aperture almost circular, slightly indented by last whorl; periostracum projects beyond margin of outer lip (V. velutina-drawing).

Up to 20 x 20 mm, but commonly smaller.

Shell white, periostracum dark brown.

Mantle edge smooth, greatly thickened; foot shield-shaped, with double-edged anterior margin; no operculum (V. velutina-animal).

Associated with tunicates, particularly solitary species such as Styela ; normally sublittoral, to 1000 m, but may occur at ELWST.

Circumboreal, extending down west coasts of British Isles to Mediterranean; deeper in the southern parts of its range (Distr. V. velutina).