Shell large, covered with periostracum, with a tall spire tending to become styliform at the apex, which is otherwise blunt; 7-8 whorls, which are swollen, sometimes a little flattened subsuturally. Shell covered by spiral ridges and growth lines. The spiral ridges are numerous, low, flat, broader than the intervening grooves, less obvious near the suture, coarser towards the base, most prominent at the periphery. The last whorl is somewhat extended basally. Aperture broadly oval to D-shaped, usually hardly distinct from short, wide, and open siphonal canal; columella nearly straight. Outer lip flared in old shells. There may be a siphonal fasciole and umbilical groove but more commonly not. The degree of subsutural flattening is equally variable, reflected in the profile of the whorls which may be a smooth curve, or flat, or even concave towards the adapical suture. Last whorl occupies about two thirds of shell height, aperture a little less than half.
Up to 135 x 64 mm.
Yellow or greenish, darker towards the apex; the colour is in the periostracum, the shelly matter being white. Throat darker.
The animal has the external features of a common whelk, Buccinum undatum save that the whitish flesh is flecked with purple, and the operculum is triangular.
British records all relate to soft bottoms off the north-eastern coast of Scotland.
Northern species which ranges across the North Atlantic from Norway to America, and extends south to the North Sea and to Newfoundland (Distr. B. turtoni).