There are quite a few 'growths' of these worm colonies on the rocks in this area. They are a community of marine honeycomb worm (Sabellaria alveolata) each of which makes a single tube from sand or shell fragments, and lives inside for its whole life apart from a short period as a larva.
Uploaded to Geograph by Richard Law on 3 October 2017
Photo © Richard Law, 3 October 2017. Licensed for reuse under this Creative Commons licence