Echinocystoida

plural noun

Echi·​no·​cys·​toi·​da

"+sə̇ˈstȯidə

: an order of Silurian fossil echinoids having small irregular spheroidal or flattened tests

Word History

Etymology

New Latin, irregular from Echinocystites, fossil genus of Echinodermata (from echin- + -cystis + -ites -ite) + -oida

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