Look like fanworms to me, but can't realy tell from the pictures.
Here is a good website to identify stuff on live rock http://www.reefs.org/hhfaq/index.html
Good luck
I have something that looks very close to the picture you posted (but the centers are almost lime green). I bought these as green star ployps and they ended up to be daisey star ployps. IMO, it looks like a type of polyp. I dont have my pics developed yet, or I would post.