East Riding Museums

Cream coloured fossil sea urchin (Cidaris), found at Sewerby. Sea urchins (echinoderms) consist of a shell (or "test") of overlapping or butting plates from which (when the creature is alive), project numerous spines or feet, held to the shell by muscles. The sea urchin uses these to get about and they feed with a toothed beak that resembles a drill bit. There are about 800 types of sea urchin, living in polar waters as well as tropical areas. The Cidaris lives in fairly deep water, in the Atlantic Oceanand the Mediterranean Sea.