I bought a pretty cool piece yesterday, and I am not quite sure of the real name of it. I searched and searched and it seems very close to Isaurus Tuberculatus, however it has no bumps on its arms/legs/appendages/whatever. I never saw it 'polyp' out in the LFS, but I sort of figured it may. It did the very first night, almost every appendage opened up. I will try to get a night picture, but I haven't jumped on the super camera bandwagon yet (next year). The ends open up and it looks almost like a very thin sun polyp. It also glows light green under my moonlights. It looks way better at night. I dropped some golden pearls in last night and as soon as the cloud hit, the polyps closed for a minute, and then even more opened up.
As you can't see the base in the picture, each one of those appendages is separate on the rock, they are not connected to a central body. Some of them share a common base, but not more than two or three of them.