Shell small, globose, ovoid, with low spire and a broad semicircular aperture bordered on the columellar side by a broad, thick callus. External surface smooth and glossy. Profile of the body whorl slightly concave along the suture. Columella rather straight, smooth; outer lip thin.
whitish background with a vivid pattern of oblique dark purplish or blackish lines arranged along spiral bands, which tend to cluster where they meet the suture; these are separated by spiral bands tinged with brownish gold; columellar callus also tinged with brownish gold.
common size :
up to 4.5 mm in greater diameter.
The only native marine species likely to be confused is Smaragdia viridis Linnaeus, 1758, which is much larger, usually has a green color with a much looser pattern of dark lines, and lacks the distinctly concave subsutural area. Some freshwater species of the genus Theodoxus can also be confused, but in that species dark lines are rather reddish and are not parallel but make a distinct, rather scale-like, pattern.
BIOLOGY / ECOLOGY
on shallow subtidal soft bottoms, probably on seagrass.