I have seen a bristol worm. He's a big one I think. He came out of a hole in the rock but not all the way. It got about 3 1/2" but the tail was still in the first hole so it must be longer. It grabbed a peace of something in the hold snapped back in to the first hole, Like fast. It was cool. the last few days these rocks have just come alive. I feel like a junky. LOL I guess I am. There are worse things right.