A reef is big. Usually they're hard to overlook but now Europe's biggest honeycomb reef has turned up in Waterford.

Until now the largest had been thought to be in Brittany. But it seems that was just an oversight and now the record books can be put straight.

As part of the 2015 Biodiversity Week, Coastwatch invited the public to walk the shore at low tide to check for reef outcrops and help measure the length and size of the reef, with kayakers and divers also taking part in the study.

Karin Dubksy the project co-ordinator explained: “Honeycomb reef is created by a small worm called sabellaria albeolata which lives inside small tubes that it builds from sand and shell - quite why we do not know. But when thousands of these worms work together they can form massive reefs along the coastline and form useful habitat for other marine life – in essence they are the bioengineers of the sea!”

Presumably those worms still building the reef - even if as Karin Dubsky says, nobody knows why