Cidaroida

plural noun Cid·a·roi·da \ ˌsidəˈrȯidə \

Definition of Cidaroida

:the oldest surviving order of sea urchins containing the most primitive of living forms, all lacking peristomial gills and sphaeridia but having an apically located anus — see cidaridae

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Origin and Etymology of cidaroida

New Latin, from Cidaris + -oida


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