Positive ID as a benign bristle worm? It seems that the presence of blue, or at least the lack of consistent overall red coloration, is one of the distinguishing factors between aggro 'worms and "friendly" 'worms? I've also seen in a couple places that the larger specimens are best removed from the tank to prevent them from getting too aggressive/exploring other food sources apart from detritus? This one is about 2" when it "contracts", and has been expelling substrate since I caught it. I've read that some places list fireworms as being carnivorous, but this one seems to have ingested grains from the tank bottom. Feedback/positive ID would be appreciated.