Pomatoceros triqueter

Keelworm (Pomatoceros triqueter)

The tube in which the worm hides at low tide is white and smooth, irregularly curved, hard and calcareous with a single prominent ridge along its back. It looks triangular in cross-section. The worm itself is small with varied colouration,  and has a crown of feeding tentacles. Similar to Pomatoceros lamarcki which has two ridges each side as well as a centre ridge. Tube width 3 to 5mm. Worm length up to 25mm.

Found encrusting and scarring rocks and shells on the middle to lower shore. Discovered on most types of coastline. Common and widespread.

Photograph taken August 2015, Meadfoot Beach, Torquay, Devon. Camera Nikon D3200, with Sigma 105mm macro lens. © Pete Hillman 2015.