(Kanmacher, 1798)
Description (shell):
Shell elongate, conical, glossy; with six tumid, semitransparent whorls; apical whorls smooth or finely reticulate, contrasting with strong flexuous costae and spiral striae on teleoconch. Spiral striae accentuated on base of shell, forming two prominent spiral keels; aperture small, oval, with thickened peristome and labial costa (varix); a deep umbilical groove but no umbilicus (M. crassa-drawing).
Size:
Up to 3.5 x 2 mm.
Colour:
White.
Animal:
Body of typical rissoid pattern, mantle edge smooth, with short pallial tentacle on right and slightly more prominent one on left. Metapodial tentacle narrow, extends to edge of foot; an additional, smaller projection on each metapodial lobe.
Habitat:
Fairly common among weeds and under stones at LWM; more common sublittorally, to 50 m, on sandy bottoms.
Distribution:
From Mediterranean to Norway; absent from continental coasts of North Sea (Distr. M. crassa).