I noticed in the sump I have a lot of these little creatures. Most are tiny I think about a centimeter in size. They are on the sand and have a red line on their back. This one is quite a bit bigger and is sitting on the pump for the skimmer and does not have the red marking. It looks like it has little pincers. I have not seen any in the tank. I would think if any made it there that my leopard wrasses would eat them. Any thoughts on what they are and if they are harmful?