Wendy, A link to this polyp thing or a link to the club anemone? This clear thing is something else, not a club anemone.
For club anemone pictures, I've seen some in an big anemone book recently. For this polyp, don't worry about it. I have lots of them in my 125, all over the substrate at one point. I don't think there is a nice collection of rock that doesn't have at least one. I have a small sponge rock with one in a black sponge. Other than stinging zoos, they really don't seem to bother much and don't wander from their hole. If they did reproduce, and I have read of it, then they could cause trouble. They did reproduce in my reef in the rubble bottom. Don't know anyone in recent times around here that has had a problem with these things. The dozens of them on the rubble at the bottom of my 125 are covered over now with green star matts, mushrooms, anemones, leathers, palythioa, sponge. etc. I'm sure they are still there, just don't see them anymore. I have a large one in a nano that I may be able to take a picture of. Will work on it...