It very well could be a purple millepora. Keep it mind that Millepora is the fire coral species, it has become a slang for Acropora Millepora and probably caused the mix up. FYI, 90% of these Millepora, Stylaster and Distichophora species arrive and are sold dead because their skeletons are not white, they are colored due to the Calcite skeleton versus calcium carbonate for Acroporas and the like.