Winkles, or topshells, fall in the family Trochidae and have shells with a circular or semicircular mouth (i.e., the aperture) that is blocked by a flexible, horny ‘door’ (i.e., the operculum) when the animal withdraws into the shell. Almost all winkles have a spiral shell that is round and squat, and are herbivorous.
Periwinkles include the littorinids, which dominate the uppermost tidal reaches of exposed rocky shores, and other small, round-apertured gastropods. All are herbivorous, feeding mainly on diatoms and microalgae.
F*CK FISH 