Ryan Photographic - Sabellariidae - Honeycomb worms
The family Sabellariidae contains 288 species in 21 genera. They are commonly known as honeycomb worms because some members of the family live in communal reefs and their massed tubes look like "honeycombs" when the worms have withdrawn. They typically have an operculum (essentially a trap door) that they can close behind them after they retract.
Sabellariids are deposit or filter feeders and mostly live in shallow water in all the world's oceans. They make their tubes of cemented sand grains, secreting a "glue" to do so. Capa, Hutchings and Peart (2011) carried out a comprehensive review of the family which can be found here.
Lygdamus splendidus Honeycomb worm
Lygdamus splendidus Honeycomb worm Puerto Galera, Philippines IMG_8100
Lygdamus species Honeycomb worm, Puerto Galera, Philippines IMG_8208. This appears to be a different species from the one above. Note the large sand grains which make up the tube.