red worm with blue hairs? BAD or GOOD?

They're beautiful and most of them are beneficial. Large eunicids, Oenone, and Hermodice carunculata are the main exceptions that make it into tanks. At 1/4" long your worm is harmless.
 
Did it look like these worms (at the base of the rock, not the one on the rock)?

worm007.jpg


Those are your everyday, run of the mill bristle worms. A real benefit to your tank.
Why, if you work with them long enough, and have patience, they will do all of your tank maintenance, except water changes :lol:
 
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