live rock roots ? mystery live rock hitchhiker?

[meherbas]

still new to the saltwater side of the aquarium hobby so please do bare these novice questions
1)my live rock seems to be growing these kind of "roots or fibers"and just curious if thats normal ?
2)just recently while studying one of my tanks i came a cross creature that resembled a (kuhli loach)but it was thin from what i saw no more than 2inches and looked like it had a cricle of teeth or britles at the tip of its head and when i took a stab at it it moved amazingly fast and from it picking at the rock i could only assume it is some type of detritivore/what is it /and is it harmful to coral, inverts, etc.?

 

[tbone212371]

It might be a bristle worm...
Can't tell without an image/ pic...

 

[harryk]

I would have to agree most likely a bristle worm but a picture would make it a lot easier.

 

[Phyl]

Bristle worms wouldn't look like they were growing on the rock. They look like catepillers. That rules those out for me.

Spaghetti worms look like roots growing on your rock. They're a good thing. They'd be a golden brown color.

Reddish brown or greenish brown is most likely algae. That needs enhanced clean up crew (CUC).

Can you describe what you're seeing? Does it change locations? What color is it? Is it fine and stringy? Bushy? Shiney?

 

[JohnS_323]

The one worm I can think of that moves amazingly fast and has a ring of teeth/bristles around the head is a eunicid worm.

Here is a pic of a 10" one we pulled from our tank a while ago:

There are mixed feeling about these. We thought it was OK until we saw it distressing a welsi brain. It *looked* like it was eating it but I'm not sure. Whatever it was doing, it had the brain in bad shape.