About Nacella concinna (Strebel, 1908)
The shell of Nacella concinna typically grows to about 6 centimetres (2.4 inches) in length, with specimens living in deep water being noticeably smaller. Its overall shape is an elongated ovate, moderately elevated cone. It has a low apex positioned slightly toward the anterior margin, angled in that same direction. About 30 faint radial ribs run across the shell, alongside a series of fine concentric lines that mark the species' annual growth rings. The exterior of the shell occurs in varying shades of pale brown and grey. The interior of the shell is dark purplish-brown for deep water specimens, but creamy-brown for specimens collected from shallow water. The mantle has a fringe made up of short tentacles. Nacella concinna occurs on the seabed of the Scotia Sea, between Tierra del Fuego and the Antarctic Peninsula. Its known range includes South Georgia, the South Orkneys, the South Shetlands, Bouvet Island, Seymour Island, Paulet Island, Wandel Island, Anvers Island and Petermann Island. It can be found across a depth range extending from the inter-tidal zone down to 935 metres (3,068 ft), though most specimens are found in shallow water just a few metres deep.
