My second hitchhiker! Yay! Need an ID.

[yunabug]

So, when I got my rock, it had been out of water, wrapped in wet newspaper for about 3 hours, so I honestly didn't expect ANY hitchhikers on it.
My fist hithers were a couple of featherdusters, who are doing wonderfully as far as I can tell.
So I was staring at my tank today, and saw a worm! I was very excited!
I need and ID, but I have no picture.
I can assume that it was a bristle worm of some sort. It was half red, half black, with white either bristles or legs on it's sides. It was moving super fast, so I couldn't get a pic.
Good or bad? And can I expect more?

 

[socal57che]

Look like this one?
They are beneficial detritovores.
You likely have more. Too many can indicate overfeeding so watch the population.

 

[yunabug]

Yeah, looked kinda like that, only the color was more defined. Like, when I say half black half red.... the color didn't fade into each other.
I'm still cycling my tank, so the only nutrients in the water is the ugly brown algae @_@

 

[cranberry]

Bristleworms have many many different "looks/colours". If it was a worm with bristles than it was a bristleworm.