Corals are tougher than you think. I have a brain coral that i received a small frag of from the National Aquarium in Baltimore. The coral is about fifteen years old and grew to the size of a soccer ball. I decided to move it and it had encrusted on one of the main rocks in the reef. So I broke the coral of and took that rock out of the reef and bleached it to kill the brain coral on it. After a 12 hours bleaching, I soaked the rock in fresh water for a day and then dried in the sun. I placed that rock back into the reef and a year later the brain coral has started to grow again and is as big as a quarter. Unbelievable.