Cerithideopsis californica, common name the California hornsnail[2] or the California horn snail,[3] is a species of sea snail, a marine gastropod mollusk in the family Potamididae.

[3] Throughout its range in California, these snails grow and reproduce from spring through fall (March–October) and cease growth and reproduction during the winter (November–February).

[3] At least 18 trematode species parasitically castrate California horn snails.

[3] After infection, the trematode parthenitae clonally replicate and produce free-swimming offspring (cercariae).

[3] These offspring infect second intermediate hosts (various invertebrates and fishes) where they form cysts (metacercariae).