Thanks Matt , I'll give it a read

brain
 

try to shine a white light(try that led t5 i lent you)(don't shock yourself)on the coral and take a picture(everything seems too blue to really see what's happening)i still think it is cryptic sponge on the coral ,but i have to see it in a more white light.you can show me when you come by

I had the same problem with some green algae on my brain and it actually had a hole in the flesh where it was, hydrogen peroxide dip 4 parts water 1 part hp for 5 minutes took care of it

Thanks , I might have to try that.