What are these?

[pro2k]

There are clear milkyish tentacles coming out of one of my rocks. I can see them reaching out as far as maybe 4 inches and retracting all the way back. Any idea what they are? I will try to post a photo. If I can't look into my gallery. Thanks! Sorry about all the algae!

 

[Paintbug]

sounds and looks like a Spaghetti worm. heres an article with some pics http://www.reefkeeping.com/issues/2002-06/rs/index.php

 

[pro2k]

That does sound right. I didn't have time to read the article yet though. Are they harmful in a reef tank?

 

[Paintbug]

not that i know of