Could be that the "bald" spots are due to a lack of light or because it's reacting to whatever glue was used to attach it to the base it's sitting on. Most branching corals will eventually encrust enough to build a solid base before it starts to branch in earnest. I wouldn't expect the bald spot to spread unless the coral becomes stressed.
No doubt the coral changed color due to a change in lighting. What lighting did the store that you got it from have the coral under and what lighting is it under now? Was the bald spot there before you bought it or was that something that developed since you've had it? |