Well being at home during the day sometimes has its surprises. It's been over a year since I added a lot of live sand to my tank, but I have never seen any of the larger worms. The only worms that I have actually seen are the spagehetti/medusa worms. To my enjoyment one of the larger worms was eating sand or ??? and I just had to video it. I don't know for sure what kind it is nor how long it is. The worm is about 1/8th of an inch thick with white feathery stuff on its sides. When it eats the mouth opens and these black mandibles pull in sand/stuff for it to eat.