Knobbed triton

The maximum recorded shell length is 390 mm. The large shell measures up to 400 mm on mainland locations, to 200 mm off island and seamount sites. The protoconch is multispiral, normally eroded except on very juvenile specimens. The teleoconch consists of 8-9 whorls with a moderately high, conical spire and convex whorls, the last one ample and making up slightly more than two-thirds of the total height. The spire whorls are vaguely shouldered, with very flat spiral cords separated by poorly defined, rather narrow interspaces, the shoulder covered by a much broader and flatter cord and commonly, but not always, bearing a spiral series of knobs, paralleled to the abapical side by lesser flat cords with or without spiral rows of knobs. The large aperture is oval in shape, with an elaborate peristome. The outer lip is flaring, thickened at a short distance from the edge and with internal denticles. The inner part of the peristome shows an appressed parietal callus continued into a foliated columellar callus, which has a raised edge overhanging the siphonal canal on large specimens, and bears indistinct ridges towards the edge. The colour pattern is very characteristic, with articulated spiral bands of light patches on the knobs and dark brown in the interspaces, alternating with medium brown uniform bands. The peristome is white with dark brown denticles on the outer lip and a brownish to reddish hue on the edge of columellar callus.