My turbo snail has whet looks like a fossilized worm on it's shell but at one end there is a tiny thing that looks a bit like the head of a feather duster only much much smaller! I tried to get a pic but can't zoom in that close without blurring. It is on the bottom side of the shell in the picture, I've seen a couple of similar things growing on the live rock by my mushroom corals - are they safe?

