ID request - Polycheate? Hydroids?

[ThunderGoose]

These came in on a piece of live rock from my LFS. The rock has feather dusters that I noticed right away and then yesterday I spotted these. They are very, very small, I needed to use my macro lens to get a good sized image. After spending a lot of time browsing the Hitchhikers Guide by Lionfish Lair I'm still not sure. Thoughts?

Thanks!

 

[Kungpaoshizi]

I think I see 3 things here? One left, one center, one right..
Left and right looks like the same kind of root, perhaps algae?
Center seems awful small to identify.. Maybe the same thing but it hasn't grown and rooted on any sand grains?