Closed Brain coral help

[whatcaneyedo]

Is the dark brown area really soft and loose? If so, siphoning it off would be the least traumatic way of stopping the spread. Use a small diameter flexible length of tubing and siphon the tissue off of the coral into a bucket then replace the removed water with newly mixed saltwater. If that works the healthy living tissue will eventually grow back over the dead areas in time. That approach worked very well for me when I received this coral which spent too much time in a very small amount of water.