When I first introduced this goniastrea to the tank, the bottom two polyps struggled, pulling flesh away from the skeleton. I assumed because it was partly shaded at that position. It has since recovered and been growing back. A couple days ago I noticed a white spot between the top two polyps, and I assumed it was skeleton showing. But today at feeding time, it was much bigger, and seems to protrude slightly from the coral.
Photos attached. Any idea what this is?
Photos attached. Any idea what this is?