Faint spiral grooves are most fully developed at base of shell.

Left: dark unbanded specimen ploughing surface of sand with its white cephalic lobes raised to act like a snowplough pushing the sand aside and leaving a characteristic wide trail with raised edges. Mediterranean coast of France, March 2023. © X. Rufray.

Right: typically banded specimen. 1: long, frail, faintly amber, translucent operculum. Cornwall, England, February 2024. © K. Raven.