<em>Tonicella marmorea</em> (O Fabricius, 1780)
Detail of the girdle and valve structure of Tonicella marmorea
It is a northern species extending as far south as north Wales in the west and Yorkshire in the east. Elsewhere it occurs across the Arctic Ocean around Norway, Sweden, Greenland and the Atlantic coast of North America.
Most common on expanses of bedrock though also occurs on stones and pebbles. It feeds by grazing material from the rock surface using its radula. It can occur in fairly high densities (40-50 per square metre) making it an important grazer within the ecosystem. It occurs very low on the shore down to depths of 200m.
- Smooth, "leathery" appearance of girdle
- Valve surface appears smooth
Size: Up to about 45mm long. Shape: Relatively narrow girdle with the shell making up 70% of the width. Valves are moderately tall with a definite keel.