Hello, 2 months ago noticed two heads died off suddenly but did not find a reason behind it so took the coral and hydrogen peroxide dipped it and put it back. 1 month later another 2 heads died off. Didn't respond and let it roll out and finally the remaining heads or semi closed and noticed something black growing on it's skeleton, any advice or should I just scrape and revive dip it? Should I be worried if it's somewhere else in the tank?