02 Calliostoma zizyphinum

02 Calliostoma zizyphinum

1: height. 2: width. 3: Ten incised spiral lines on base of body-whorl disappear into shell on parietal lip which is darkened by slight glaze. 4: top of body whorl. 5: Obtuse adapical angle. Aperture 33% shell height.
23mm high. Portland Harbour, Dorset, U.K. April 2012.