Exocycloida

plural noun

Ex·​o·​cy·​cloi·​da

ˌek(ˌ)sōˌsīˈklȯidə

: an order of sea urchins comprising forms with the periproct posterior or oral in position and including the heart urchins and sand dollars

Word History

Etymology

New Latin, from exo- + cycl- + -oida

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