I really am led to believe even from the beginning that OP probably has the bearded fireworm, but I'm also in desperate need of first hand data, because I'm not entirely convinced that everything accused of being the bearded beast is the bearded beast. And in light of data I've received this last week, im not quite as sure the bearded fireworm is quite the devil we all are led to believe he is. Yes he can be a killer of slow moving creatures, yes he eats a couple species of corals, but recently ive been reading several once accepted species of Hermodice in technical literature have been consolidated, but I am suspicious that they are not necessarily all coral eaters, some populations in the wild don't seem to destroy corals all that much while being ferocious consumers of grazing echinoderms.
I'm trying to get more reefers to refer to them less as bristle worms and more as polychaetes. Some more technical literacy will help us not sentence boatloads of innocent animals to cruel wasteful deaths due to arbitrary and ill defined names