Shell. A tall, conical shell, rather fragile, opaque and dull, covered with a periostracal layer usually absent from a triangular area alongside the inner lip. There are 7-8 swollen whorls which form a slightly cyrtoconoid spire (apical angle of large shells 30-35°, of small ones 45-50°). The whorls meet at deep, channelled, rather oblique sutures which He well below the periphery of the upper whorl. The subsutural area of each whorl is commonly flattened. The surface is marked by spiral ridges and growth lines. The former arc low, narrower than the spaces between, and rather sharply topped; they are numerous — 35 or so on the last whorl, about 12 on the penult — more widely spaced at the periphery, small and close subsulurally, and frequently alternately larger and smaller,- especially on the last whorl. The growth lines arc markedly curved, prosocline at the adapical suture, opisthoclinc at the abapical, and flexuous on the last whorl.
The protoconch has two planorboid whorls; the first is smooth, the second with the same ornament as the rest of the shell: it may measure about 1 mm in diameter, and is sharply separated from the rest of the shell, with which it is co-axial. It is usually badly eroded.
Aperture. A broad oval, not angulated adapically, extended basally into a canal, and surrounded by a peristome. The outer lip arises below the periphery of the last whorl, then curves smoothly to the base, with little or no change of curvature at the origin of the canal. It has a broad anal sinus in its adapical half and may turn out a little below this. The columella is short and straight. The inner lip forms a broad and sometimes thick expanse with curved, raised edge, underneath which may be an umbilical groove. The canal is short, broad, and widely open.
Colour. The shell is while, the periostracum buff.
Size. Up to about 80 x 35 mm. Last whorl = 65-70% of total height; aperture = c. 48% of shell height.
Animal. As in other Colus spp.
Colour. White, with some dark points and streaks.
Geographical distribution. From the most northern parts of the North Sea north to the Arctic. It extends into the Skagerrak and Kattegat. It does not seem to have been recorded in waters nearer the British Isles than those between Shetland and the Faroes.
Habitat. On muddy bottoms 35-1500 m deep.
Food. Unknown.