Cidarina cidaris, common name Adam's spiny margarite, is a species of sea snail, a marine gastropod mollusk in the family Eucyclidae.
[1][2] The height of the gray to grayish white shell attains 20 mm.
(Original description in Latin by Carpenter) "Testa magna, conica, Turcicoidea, tenui ; albido-cinerea, nacreo-argentata ; anfr.
(decollatis), norm, vii, subplanatis, suturis alte insculptis ; superficie spirae tota valide tuberculosa, seriebus tribus, alteris postea intercalantibus; peripheria et basi rotundatis, carinatis; carinis circ.
This species occurs in the Pacific Ocean from Alaska to Baja California.