Very weakly calcified, amber-brown shell consists mainly of periostracum which, when live, forms a velvety surface often mistaken for the mantle of Lamellaria or a dorid seaslug (see image 35) .

1: flaked off section of the flimsy, fragile, calcified inner layer; increases translucency.
2: short spire which barely protrudes from the outline of the shell.
3: apex is recessed below the previous whorl.
4: sutures deep, when not concealed by periostracum. Moray coast, north-east, Scotland, May 2018. Leg. C. Rickard.