plural noun
Cas·​sid·​i·​dae | \ kəˈsidəˌdē, ka-\

Definition of Cassididae

: a family of usually large marine gastropod mollusks (order Pectinibranchia) having thick heavy shells of which many are used for making cameos — see helmet shell

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History and Etymology for Cassididae

New Latin, from Cassid-, Cassis, type genus + -idae

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