Periwinkles have a dark brown to brownish-gray shell that is up to about 1 inch long. Periwinkles are sea snails classified in the Phylum Mollusca and Class Gastropoda.
Periwinkles are native to northwest Europe, but has been introduced to the eastern coast of the U.S. and Canada, most likely the ballast water of ships in the 1800's.
Periwinkles feed on algae, which they scrape off of rocks using their radula. They are edible snails. While they are not a common meal in the U.S., they are eaten in Europe, Africa and Asia.
