Lugworms are found in large numbers on the mud flats. Sport fishermen use them as bait. Lugworms injest bites of bottom sand and filter out edible plankton in their intestines. In order to get enough to eat, the animal has to process a lot of sand. It lives in a U-shaped tunnel. It eats sand from one end of the tunnel and whatever is indigestable is pressed out of the body at the other end of the tunnel. This is where the typical spaghetti piles of sand come from.