About Coelotrochus viridis (Gmelin, 1791)
Coelotrochus viridis (Gmelin, 1791) has a shell with a length ranging between 15 mm and 25 mm. The shell is solid, conical in shape with nearly straight outlines, and false-umbilicate. For the upper surface sculpture, each whorl has 5 series of rounded bead-like granules. Numerous very minute spiral striae are visible between these granules, and oblique incremental striae are prominently visible in the interstices of the minute striae when viewed under a lens. The base of the shell has concentric striae that are unequal in size, and these striae disappear toward the outer edge. The shell is coloured dull grey, whitish, or greenish. The apex is acute. The protoconch is very small, with 1ยฝ whorls that have a slightly rugose surface. There are approximately 7 whorls, which are nearly flat, or sometimes slightly bulging at their upper and lower margins. The body whorl is strongly angled or carinate at its periphery, and the base of the shell is plano-concave. The suture is rather deep. The aperture ranges from suboval to quadrangular in shape and is nacreous on the inside. The outer lip is convex and sharp, with a smooth marginal band on the inside. The outer portion of the outer lip is narrow, white, and opaque; the inner portion is broader, iridescent, and smooth, and the section further inside is lirate. The basal lip is thickened and subdentate, and it joins the columella in a regular curve. The columella is oblique, with a deep fold near its insertion, and is smooth on the inside. The umbilical area contains 3 to 4 spiral ribs, and their interstices are nacreous. The umbilicus is narrow and deep, or is partly filled in by a white callus. The parietal wall is transversely striate or nearly smooth, and covered with a light brown callus. The soft body of the animal is yellowish-brown. Its foot is reddish or purplish-brown. The filaments are white, with 3 filaments located on each side. The head-lobes are smooth and rounded, and are joined across the head. The eyes sit on rather long white peduncles. This marine species is endemic to New Zealand.
