Your bristle worms will die back as food runs out until they reach a population max.....great cleaners and worth leaving there. I constantly remove large ones from the nano to populate the big tank using long plastic tweezers at feeding time.
As said they will irritate your skin on contact and, if fire worms, may sting a bit as well !!!
Either Joe's Juice or Aiptasia X. I know Joe's Juice is a concentrated calcium similar to Kalkwasser. It worked for the couple of little ones I had. It is difficult though, they pop in side the rock very quick when you go anywhere near them.