Home > Invertebrates > Shells > Rissoidae > Rissoina ambigua

Created 2/21/2026

Family Rissoidae

INDO-PACIFIC / HAWAII

Rissoina ambigua




Makapu'u tidepool, Oahu, 6.5mm
  
   

AMBIGUOUS RISSO

Very common under stones or rubble in shallow water.  Solid, glossy, whorls nearly flat with 20 or more fine axial ribs on the last whorl and fine spirals between ribs on base only.  White, pink, yellow, orange, sometimes with diffuse brown spirals.  Attains 0.2 inch, 7mm.  Red Sea to Japan, Hawaii, and French Polynesia.  Rissoina materinsulae is a synonym.