If you're in the states, Bayer will get rid of the nudi's. Is it an encrusting monti, cap or digitata? I can't tell from the picture. If it's encrusting, you might want to look into using revive and rinsing the heck out of the rock before putting it back in the tank. If you are using bayer, make sure you have multiple containers to rinse the coral off before putting it back in your tank, especially if it's a larger coral. You don't want any residual poison getting into your tank.