Lugworm faeces pile in the Red Sea. This species of tubeworm is unidentified but it may be the lug- worm, Arenicola, or a close relative. Faeces piles like these, of Arenicola, exposed at low tide, are well known by anglers who dig out the lugworm and use it as bait. The worm inhabits a U-shaped tube in the seabed. Found usually in the lower section of the tube, the worm filters sand by creating a water current through the tube and ingests sand particles. From the other leg of the tube, a spiral strand of faeces is excreted (as seen here). Through this water current the lugworm gets oxygen, and planktonic particles trapped in the sand act as food.