What are these?

[clownfishplace]

I was looking over my tank on night, and to my suprise i have foud three catapiller like thing in my tank that live in the life rock. Ranging anywhere from on inch to 4 inches in length. They look like long hairy catapillers with flat tails. I have no idea where they came from, and am unable to get a picture of them.

[edawgm]

Here is a like with a pic. Is this what you saw?
http://www.wetwebmedia.com/bristlewmfaq3.htm

[RayAllen]

Sounds like a bristle worm to me. Does it look like this

http://www.reefseekers.com/PIXPAGES/Bristle_worm.jpg

If so they are good for the tank, but you dont want to touch them. Where gloves when working in the tank.

[clownfishplace]

Yes, thats it. But the thing that I don't understand is my water condition are good every thing like nitrates test "0". I have only three fish and only feed a small amount of food once every two days. I don't know what is sustaining them, or should I even be worried about them? They don't seem to be doing any harm.

[Ram_Puppy]

bristleworms are beneficial to a tank... they eat your fishes poop, waste generated by your rocks, and general detrius.

[apedroza]

Just be careful they can get out of control and if you touch them they sting like crazy!!!!

[jrnannery]

If you decide you want to control them - not eliminate them - but control them, get an arrow crab in the tank. They are awesome to watch, and remind me of the bad guys in War of the Worlds. It is especially cool to look in and see them holding half a bristleworm in its claws while striding over your reef.