Any of numerous clypeastroid sea urchins (sand dollars) of the genera Melitta, Rotula and Encope, with one or more perforations resembling keyholes.

Any sea urchin of the genus Rotula having a round, flat shell; a type of sand dollar.

Any of the genus Clypeaster of echinoderms. See Clypeaster

plural of cake urchin

plural of keyhole urchin

plural of nano-urchin

plural of street urchin

plural of wheel urchin

Resembling or characteristic of an urchin (mischievous child). / Resembling or characteristic of a sea urchin.

plural of urchiness