Zool. Pl. -idia. Also -ideum. [mod.L. (Lovén), f. sphæra SPHERE sb.] One of the numerous minute rounded bodies attached to certain parts of sea-urchins.
1877. Huxley, Anat. Inv. Anim., 572. In some genera, these sphæridea … are sunk in fossæ of the plate to which they are attached.
1888. Rolleston & Jackson, Anim. Life, 559. Sphaeridia … occur on the peristome and ambulacra…. Structurally they are modified spines, spherical or oval in shape.
