Looks like bryopsis to me too. It's not fun to rid a tank of, so you may want to treat those frags ASAP before it spreads.
My treatment for zoanthids is rougher than the average person, but after I got zoanthid eating nudibranchs I use it every time. I have never lost a polyp from it, but it makes them a bit unhappy.
I use iodine to treat all corals, but with zoanthids I follow it up with a peroxide bath. I do 50% tank water and 50% peroxide (the regular 3% concentration brown bottles). I leave them in there for 4 minutes (they will fizz) and return them to the tank. They may not open until the next day, but it works for nudibranch eggs. It's probably way overkill for bryopsis, but I collect wild zoanthids so I like to play it safe. Who knows what they could carry?
Iodine won't treat bryopsis, but peroxide sure does! Manual removal does not work well IME.