e·chi·nus 
(ĭ-kīnəs)
(ĭ-kīnəs)n. pl. e·chi·ni (-nī′)
1. A sea urchin of the genus Echinus.
2. Architecture A convex molding just below the abacus of a Doric capital.
[Latin echīnus, sea urchin, from Greek ekhīnos, sea urchin, hedgehog, from ekhis, adder, viper.]