I bought a very small piece of live rock recently because of what it had growing on it, a little zoa colony. I could see three little polyps. But when I got it home I discovered that there were closer to eight on there they just didn't like the water at the LFS. Once it got settled they opened all the way up, beautiful. I think started seeing the various worms coming out. Since then I have made it a point to watch it carefully once the lights go out. No stat fish, but there is a really cool looking little feather duster.