I guarantee they are eating your leather. If you have other similar corals they could be in trouble as well. If it were me, I would remove all the leathers to
QT, treat them to kill the present
nudis and let the ones still in the display starve.... but I know most peeps won't do that.
If you put 8 drops of salifert exit in 3 gallons of saltwater and dip the colt for 15 minutes, it will kill the present
nudis. It won't do anything for the eggs which will need to be removed manual... inspect the coral well. And it won't do anything for the
nudis in the display tank that will crawl back on. At the end of 15 minutes shake the coral in the solution vigourly. Then place in clean
SW for 15 minutes more and then return to wherever you choose to return it too.