Kelp Shell. Shell elongate-conical, thickly imperforate, polished shining unicoloured rod or brown and spaced lighter coloured spiral lines; surface closely microscopically spirally striate; spire long, apex acute; whorls seven, slightly convex, body whorl long and rounded at the periphery; aperture one-third of the shell height, vertically ovate, brilliantly iridescent green, sometimes bluish, within and spirally ridged peristome thickened: columella vertical, toothed below the middle. Diameter 16 mm., height 40 mm.