hairy centipede looking thing came out of my live rock

Very light colored hairy worm/centipede looking thing crawled out from the bottom of my live rock then disappeared again. What is this and is it good or bad for my tank?

 

maby bristel worm (google it)

 

This is exactly how i descirbed what i saw in my tank a few months back. It is more than likely a bristleworm. They are great for the sand. Just be careful with your hands in the tank from now on. They sting bad!!!!

 

Yep bristle worm. Some are harmless and some eat corals. I always remove just to be safe

 

Either a bristle or fire worm. I have seen both in my tank. I wish I could catch the fire worm I have seen but bristle worms are harmless. I catch when I can. Also seen p-nut worms bet I hear they are harmless.

 

The bristle worm in my tank actually helps stir up the sand a bit at night...I think he helps