Family Serpulidae (Serpulids)
Tube width 3-5mm.
Worm length up to 25mm.
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.
Found encrusting and scarring rocks and shells on the middle to lower shore. Discovered on most types of coastline. Common and widespread.