Shell globose, ovoid, very solid with low spire and a broad semicircular aperture bordered on the columellar side by a broad, flat callus. External sculpture with alternating broad and narrow, very flat ribs, crossed by indistinct growth lines; sometimes appearing quite smooth on old, worn specimens. Columella with a shallow notch in its median part, hardly denticulated if at all. Inner surface of the outer lip with inconspicuous denticles, or nearly smooth.
variable, with generally irregular black zig-zag, confluent flames on a white background, more rarely with black pattern forming spiral bands, or with reddish hue instead of black. Inside of aperture and callus whitish, tinged sometimes with green, the outer color pattern apparent on the very edge.
common size :
up to 25 x 20 mm in the Red Sea, the two Mediterranean specimens smaller.
This is the Red Sea representative of a species group which includes Nerita albicilla Linnaeus, 1758, a species with a broad Indo-Pacific distribution which differs in having more conspicuous columellar and labial denticles.
BIOLOGY / ECOLOGY
on rocks near sea level.