The guy who sold it to me said it was an acan, but it doesn't look like any of the acan pictures Google pulled up. Is it? What is the difference between acans and favia/favites? They are all brain coral, right?
These corals can be hard to tell apart. Favites, like pineapple coral, share the ridge between polyps, Favia, like brains, do not. Each Favia polyp is surrounded by its own ridge.