Diagnostic characters
Shell small, flattened, semitransparent, glossy, with a low, obtuse spire and a very large umbilicus. The whorls bear spiral ridges. The aperture lies in a prosocline plane and appears nearly circular when the shell is held upright. The mantle skirt has two marginal tentacles on the right. Operculum with about 12 turns.
Other characters
There are 4-5 whorls, rounded in section, with deep sutures placed on the apical side of the periphery of each whorl. There are usually eight or ten (up to twelve) spiral ridges on the last whorl, 5-6 on the penult, 4-5 on the previous, the rest smooth. The base of the last whorl lacks ridges, but a further series of four or five appears on that part of it which lines the umbilical space. Other whorls exposed in that space also show ridges. The outer lip arises level with spiral ridge 6, 7, or 8 and shows a small peripheral bay and slight basal projection; it is crenulated by the ends of the ridges. White. Up to 1.25 mm high, 2.75 mm broad; last whorl occupies 80-85% of shell height, aperture about three quarters.
The animal has a narrow snout which is a little bifid at the tip, and two long and delicate tentacles, each with a basal eye. Males have a slender, sickle-shaped penis. The foot is narrow with recurved anterolateral points. Whitish with opaque white speckles, the snout pinkish.
C striatus is a very rare animal at the latitude of the British Isles, where only a few shells have been found on western coasts. It is a southern species occurring from the Mediterranean north to Britain and Ireland, living on muddy bottoms at about 30 m deep. It appears to eat material adhering to sand grains (Fretter, 1956).