I had a piece of rock that had one as hitchhiker, dipped it and this enormous 12 inch long one inch wide brissleworm came out. This was huge, red and not going back into my display. left him in the frag tank, no sand. just scurrying around eating detrius. im just curious to see how big these things will really grow too.
Yea bristle worms can be beneficial but also harmful I have seen them take food from corals as well as destroy them. I have tons in my system I pick them out as much as possible. They will burrow into colonies like acans,sun corals wellso brains etc etc and then at feeding time just pop out and steal food from the animal