tentacles under a LR

I bought a small piece of LR with one brown polyp on it and it's starting to open up today, so I spend more time looking at it and saw some tiny tentacles (with a dot at the end) waving underneath that rock. They are waving upside down. I don't see a body. What are it be???

Thanks!
GKW

 

I don't know for sure since I can't see it but my guess is it is a type of worm.

 

Except for the dots, it could be a vermatid...look closely - is it spinning a web? If it is, it is a vermatid, a harmless stationary snail-like creature. It is fun to watch it "fish" for food.

 

Possibly a spaghetti worm(Terebellid).

 

For some reason I could not get the actual image to send properly in my reply message, so here's a URL that shows a great picture of a Spaghetti Worm...
http://www.pirx.xom/gallery/worms/sworm01. It's image 5 out of 13.

 

Thanks guys! Yeah, it is a spaghetti worm.That's pretty cool. I assume it is good to have it in my tank, right?

 

yes! they are good, don't bother anything. Just another beneficial organism living in or on your live rock.