Hitchhiking coral ID?

[SuncrestReef]

I had a zoa colony that has been overtaken by this brown coral which started off as a tiny polyp in the middle of the colony, but has since grown pretty large. Any idea what it is?



This is what it looked like 6 months ago when I first noticed it taking over the zoas:

 

[KJ]

Look like Galaxea. @DSC reef

 

[reef lover]

+1 galexea

 

[SuncrestReef]

Look like Galaxea. @DSC reef

+1 galexea

Thanks!