Howdy Here is my ipinion: You might be lucky, and if a piece of one did not break off, your tank might be ok. You should remove the rock from the tank, treat and then but the rock back in your tank when all the aiptaisa are gone. This will be a difficult task. I do not think you can actually kill them all while keeping anything else alive on that rock. The smallest piece can grow into new ones. To raise them for study, they stick them in a blender, pour that in a tank with rock, and let it rip. You can try to kill them with chemicals. Aiptaisa-X, Lemon Juice, Vinegar...ect. This spot treatment usually results in failure. Natural remedies are the best. Peppermint shrimp, Lysmata Wurdemanni , Berghia Nudibranch, Berghia stephanieae and the file fish are good options. However there is no guarantee they will get them all or even like them for dinner. Like people they don't always like what I'm serving for dinner. If you can have the fish or shrimp as a permanent resident of your tank they can keep them under control. You might have to kill off a big one once in a while as they seems to only like the young tender ones. I wish you luck. I have them in my 600 gallon tank and my 2 peppermints keep them under control. They do munch on a coral once in a while, but what can ya do.