Description

 The calcareous tube of Pomatoceros triqueter is 3.5 mm wide and up to 25 mm long. It is white, smooth and irregularly curved with a single, median ridge that ends in a projection over the anterior opening. The operculum bears a shallow, dish-shaped plug (ampulla) which is often conical distally, and may have projections on the crown. The colouration of the body is bright but variable, and the crown of tentacles (radioles) are banded with various colours.

• May be confused with Pomatoceros lamarcki, the tube of which differs from Pomatoceros triqueter as it has two vestigial ridges, one on each side, in addition to the median keel. Further differences can only be seen when the worm is removed from its tube (Hayward & Ryland, 1995). Further distinction between the two species can be obtained by using biochemical genetics, as described by Ekaratne et al. (1982).
  
• Males are cream in colour whilst females are bright pink/orange in colour (Thomas, 1940).