|Lugworm, Arenicola marina, casts on the beach at Ballyholme, Northern Ireland|
The lugworm, or sandworm, is a large worm of the phylum Annelida. Lugworms make the coiled tubes of sand that are a familiar sight on a beach at low tide but the lugworm itself is not seen except by people who dig them up from curiosity or to use as fishing bait.
The lugworm can grow to a size of about 9 inches (22 cm). Its body is segmented, like that of an earthworm. It has bristles in the middle of its body. It is a polychaete. It also has well-developed blood-vessels, and gills to breathe in the water.