What is this?

[INVRacing]

Hi guys, I'm new to the saltwater community, let me give you my tank background. I've started cycling the tank in Nov 2010, and added my first 3 chromis a week ago, they are fine. All water chemistry is good. Yesterday, when I had the lights turned off I noticed some bugs coming out of the sand and rock, are they good or bad? Please help

Tank info:
120g saltwater with 25g sump/ refugium, vertex 180 skimmer
2 inch sand bed
100 lbs live rock
3 green chromis
1 lawnmower blenny
4 nassarious snail and 5 turbo snails so far, eventually will be adding corals.

Thanks

 

[Kurt_Nelson]

Picture on the left kind of looks like a bristleworm. If so... good janitors to have. The other picture I can't really tell.

Here's a couple good "hitchikers ID" sites that might help clear things up...

Xtalreef
Live Rock Hitch Hikers