The Honeycomb Worm (Sabellaria alveolata) builds reefs out of coarse sand or ground shells that have been cemented together. Each little hole is like a worm apartment where a worm lives and feeds.
They are filter feeders, extending feeding tentacles into the water when the tide is in to catch any tasty plankton floating past.
Each reef is anchored to a solid surface like a rock, so these worms are only to be found in areas where there are rocks in a sandy beach. They can be found on many of the beaches around the Waterford estuary particularly on Booley Bay.