Simnia patula

(Pennant, 1777)

Description (shell):
Shell convolute, elongate-oval, drawn out into apical and basal canals; thin, polished; juvenile shells (<5 mm long), with short spire. Fine sculpture of low strap-like spiral striae; appears smooth to naked eye. Aperture curved, wider below parietal bulge of last whorl; apical canal short, basal canal wide, bordered on left by ridged columella.

Up to 22 x 12 mm.

White or yellowish.

Snout short, no proboscis; mantle drawn out anteriorly into a siphon, which projects from basal canal; lateral extensions cover most or all of shell in active animals. Foot large, elongate, with posterior pedal gland on sole and double-edged anterior end; no operculum.

Sublittoral, associated with coelenterates (Eunicella , Alcyonium and Tubularia ) on hard substrata from 15-75 m.

Distributed from Spain to west Channel; not common (Distr. S. patula).