Lanice conchilega are commonly known as the sand mason worm, they are a species of burrowing marine polychaete worm. They build a sand tube which projects from the seabed, with a fringe at the top. The tops of the tubes can be spotted on beaches at low tide. When the tide comes in, they feed using a crown of tentacles to catch passing particles. They can be found alone or in dense beds of thousands of individuals.