Periwinkle (Littorina sp.) Tracks in Intertidal Zone

These lines in the sand are from the movement of periwinkles. I took this shot during low tide, but when the tide is in, the snails cruise around on the sand and over rocks, leaving these tracks. They move using their foot, which is divided into a right and a left half. The snails move the halves alternately in order to propel themselves forward.

Habitat: Mudflat