Going to try a diy bristleworm trap. Maybe a coral banded shrimp or arrow crab. Also going to look into some halichores wrasses and a possible bird wrasse. Also the only other issue is that I have had a Trochus disappear too and have found 4 dead hermits in the past 2 weeks so it makes me think that something is hunting them down like a fire worm.
Yep, I was going to suggest a trap. That way you can identify and know what kind of worms you got. I suggest putting the trap in 45 min before lights go out. Not sure where the tank is but try to have room lights out. I’ve noticed when I viewed my tank a hour or two after lights go out. I witness my common bristle worms swarming the sandbed and LR’s… Usually back in hiding 3 hours after lights out. They even climb up a corner of my aquarium in large numbers . It’s usually only one corner. North facing if that relatable…

(Ladybugs have their favorite direction

) None of these guys are large. They stay small. If I was to overfeed they would populate heavily but not get huge. Getting off track. If you put the trap in 45 min before lights out and check 1-2 hours after lights out., you might already have a good sample size and can pull the trap. That way the bait in the trap doesn’t soak long and pollute your water….
I got fireworms in my first tank from a coral or cycled rock I got from LFS. It wasn’t the bearded fireworm but they were really plump and long. They looked like spiky fat earthworms and they populated heavily…. I’ll try and find a picture. I say this because I’m cautious on any bristle worm that doesn’t look like the common bristle, that we know is safe on our tanks.
I know there are other non reef threatening bristle worms. I would get nervous if they are really red around the bristles or bristles look different than above…. Better be safe and deal with the situation now than wait and be overwhelmed…. You mentioned tearing down the tank. Don’t do that. You got this!
I think I had Hermodice carunculata
Which is a bearded fireworm I guess. I just looked it up. Definitely looks different from the bearded fireworm I usually see. Top picture is what I think I had and bottom pic is the typical type I bearded fireworm I see in pics and read about in articles.
The identification of Worms found within live rock and live sand
chucksaddiction.thefishestate.net