Could be that or it may be worms? I think they are called brown worms & they live in a tube almost like a feather duster (duster cluster) and they spit out this white slimy looking web, catch food particles in it then pull it back in and eat! They start off pretty small and are hard to see, but they are supposed to be good for your tank. At least thats what I've heard. I have one thats getting huge and it hides under my harry mushroom. Wish I knew how to post pics. Maybe you can so we can see!!! :thinking: