Clio pyramidata Linnaeus, 1767 forma antarctica Dale, 1908
Shell transparent, straight, conico-cylindrical in shape. Cross-section near embryonic shell circular; fully grown specimens have depressed ventral side near aperture, so cross-section here is more half-moon shaped. Lateral sides only developed in uppermost part of shell. With faint dorsal and broad ventral ribs close to aperture, lateral ribs bordering the ventral side, developed only near shell aperture. Growth lines and prominent and strong transverse wavy sculpture. Transverse striae cause shell to resemble that of Hyalocylis striata (Hyalocylis striata, Hyalocylis striata 2, Hyalocylis striata 3). Dorsal aperture border slightly higher than ventral. Reddish to dark-brown visceral mass visible through shell wall. Embryonic shell pointed, separated from rest of shell by constriction. Shell length: 17 mm.