Hey, it is not that bad actually. Bristle worms are good worms as compared to bobbit worms. Bristle Worms are a type of segmented worm that is generally viewed to be beneficial to a marine aquarium. Though when there are too much of them it is not that good. You should check out this site that I used when I found a
bristle worm [arcreef.com] in my own aquarium. My friend who has had an amazing aquarium for a long time recommended me this site. Hope it helps!