Please help on ID

[TarheelReefer22]

I picked this up about a month ago from my lfs and it was completely white and bleached out. The only way I knew it was alive was that there were still polyps. When I got it it had started to encrust on the plug but you can see how much it has grown since. In the last two weeks it started getting this lime green coloration. Please help give this guy a name!
Montipora sp?

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[Frick]

It's a Montipora species, but really tough to tell which one based on the size? Can you take a pic when the polyps are retracted? The texture could help narrow it down.