What are these parasite-looking worms?

[Darryn Lyon]

I Apologize for the picture quality, I tried to nab the best photo I could, but we were moving around some live rock to accommodate some coral we got, and there were all these white parasite-looking worms, that you can kind of see on the white live rock. Are these tubeworms? Are they detrimental to the tank?

 

[helen ann]

Hard to see in the pic. IMO some sort of hard tube worm.
You can check here ... http://reefkeeping.com/issues/2003-05/rs/index.php