I vote C. arnazae..
Below r some writing and background few years back, Previously, C. arnazae a,k,a C. parasema...
http://gobiestogrizzlies.blogspot.com/2008/05/demoiselle-taxonomy-in-distress.html
Cheers...
It shld be Pavona family, scientific name Pavona decussata, common name = Cactus Coral/ Leaf Coral Potato Chip Coral or Lettuce Coral.
There is also some close family like Pavona cactus, Pavona explanata, Pavona maldivensis or Pavona venosa with different coloration.
nice sps...