Shell a moderately tall and moderately broad cone. Spire is slightly cyrtoconoid. There are 5-6 gently convex whorls, those in the spire often with a pronounced spiral groove just adapical of the suture. The last whorl may be smoothly rounded at the periphery or show a distinct angulation there. Last whorl occupies about 60 % of shell height. Sutures are slightly incised. Growth lines only a little prosocline and usually curved. Aperture usually with gently flaring base and often with spiral ridges on inside of outer lip (if it bears internal ridges these number 6-9, each ending in a small projection placed a short distance within the edge of the lip). Aperture occupies 35-40 % of shell height. Umbilical groove narrow and deep, umbilicus a chink. Tooth prominent, arising at edge of inner lip.
Up to 3.8 x 1.8 mm.
The mentum is grooved dorsally and has a bifid tip, each lobe rather tentacle-like. The tentacles are flattened, triangular, each with a lateral groove and slightly swollen tip; their bases are joined across the midline and the large eyes lie close to one another in line with the inner edges of the tentacles. The foot is large, its anterior edge embayed in the midline and expanded at the lateral margins. White, with numerous opaque white markings, one at the tip of each tentacle.
Found 10-150 m deep, usually in association with the starfish Astropecten, on which they live and feed.
Occurs from the Mediterranean to Norway (Distr. O. conoidea).