I have had this coral for 5 years. It doesn't show up so good in the photo but one new polyp came in with way less color than normal. I thought it would color up after a while but it has started to creep into the polyps next to it. It had a similar thing but not really the same thing a couple years ago. My alkalinity had gotten low and when I got it back up and kept it at 9, it healed up and has been fine ever since. Perimeters are now and have been stable. I have had sps and lps in the tank for a good while and every thing else is doing just fine. I may have it in a little more light than it needs and thought I would put it in a bit lower light and maybe do a iodine dip but thought I'd ask if any one knew what this was first.