Whats on my Frogspawn?

[mdenesha]

Anyone recognize this? It started out small and stayed the same size for a while, but it has recently grown larger.

 

[reefman]

its call coral recession

 

[mdenesha]

And this is usually caused by? Last time I noticed recession was when the head was splitting, but this is different because it started in the middle compared to the base - I recently moved the tank. It is now closer to a window which has resulted in a slight cyano bloom, possibly related?