Category:Spatangoidea

Spat`an*goi"de*a, n. pl. Etym: [nl. See spatangus, and -oid.] (zoöl.)

Defn: an order of irregular sea urchins, usually having a more or Less heart-shaped shell with four or five petal-like ambulacra above. The mouth is edentulous and situated anteriorly, on the under side.