[LeslieH]

Probably a capitellid. These are primarily sediment dwellers and feed by selectively choosing organic particles or by swallowing sand grains & digesting the attached organics. They don't have jaws; instead they have an eversible sac called the proboscis which they used to engulf particles. the proboscis can also be used to help them move through the sediment. They expand the sac & use that as an anchor to pull themselves through the sand.