Per "Reef Secrets" by Nilsen and Fossa (2002)...
Open Brain Coral -- Trachyphyllia geoffroyl
to 20 cm (7.8 in) across
Lighting -- Contains symbiotic algea and needs moderate to high intensity lighting.
Water quality -- Demands excellent water quality, including calcium supplementation for skeletal growth.
Feeding -- Responds well to occassional meals of meaty foods.
Notes... With large, fleshy polyps, this is one of the most distinctive and oldest species of stony corals in the aquarium hobby. Generally hardy, but sensitive to green algae invading the skeleton.
Of course, this is IF I have managed to match your pic with the one in my book correctly
