sphaeridium

noun

sphae·​rid·​i·​um

-ēəm

plural sphaeridia

-ēə

: one of the small organs found on or buried in the test of all recent sea urchins except the Cidaroida suggesting statoliths in structure and possibly subserving a similar function

Word History

Etymology

New Latin, from sphaer- + -idium

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