These tiny snails, about 2 mm, are virtually unknown as few recognize them hidden among grains of sand or on green algae as here. When one of its predators, the six-armed seastar Leptasterias pusilla approaches, the little snails flee while raising their beautiful protective mantle as this one is starting to do. We arranged this encounter in our lab.
Prominent flanges serve to strengthen the shell. A 'tooth' near the aperture may be used to pry open bivalves. And the radula is used to bore through calcareous shells of prey such as barnacles and bivalve.
Adult Ceratostoma females may produce 40 of these egg capsules yearly, each containing 30-80 eggs. Larvae metamorphose within the egg capsule and young snails emerge.