The shell is somewhat similar to that of spinosus Schreibers, but with a lower number of primary ribs on the free valve (6-10), and the spines are not white. The interspaces between the ribs bear thin radial striae with minute spines. Inside white, with coloured margins. above and below: a specimen from 12m deep, Sidna Alli, Herzliya, north of Tel-Aviv, NW. Israel. 82mm.