If you are talking about just the feathers dropping off, it can grow a new crown. Don't be concerned if it takes a week or even two before it starts growing new feathers. I had one that did that after I had to pry it off a rock and move it because the tube was bugging one of my corals. If the whole worm came out, I understand it can grow a new tube, but unfotunately it is very vulnerable to being eaten when it does not have the protection of the tube. Also, FYI, if you have a survivor, don't worry about adding anything extra to the tank to feed it. It will filter feed out of what is already in the water.