lugworm

Short definition from Wiktionary

Noun

1. 1
   Any of several species of large marine annelid worm of the genus Arenicola: especially the northern lugworm (Arenicola marina), whose coiled castings can often be seen on beaches at low tide.
2. 2
   Any of several species of large marine annelid worm of the genus Arenicola: black lugworm (Arenicola defodiens).