I have spotted an unknown critter in my tank. It looks a bit like a centipede when he stretches out put when it notices me it shrinks in size. I do not see any eyes and I know he can move around because I saw him in another rock the other day. It is a light brownish red color. I think he was just eating my feather duster. Not from the tip but rather from the base. I have also had a couple of crabs strangely die I am wondering if it is him? I do not have a picture and don't think he would stay still for me to get one. Has anyone any suggestions? Or seen anything matching this description?