Green plating monti

[Hp1836]

Got a chunk of green plating monti a while back. It broke into 3 small pieces when acclimating and all have been doing well. They are all in seperate areas of tank and all of a sudden the center of all 3 simultaneously turned grey. The little mouths are still there just the background color of the skeleton is no longer grey. Any idea what could be causing this?

 

[Mr. Mojo Rising]

a picture will really help, along with water parameters and tank age, otherwise we are just guessing. But the green plating monti is an easy hardy coral, it needs high light and high flow along with stable reef parameters, these are the first things to check.

 

[Gumbies R Us]

Pictures?