The coral expert coral sellers around here say to only get the Australian ones. They have been well cared for during collection. The others (usually more colorful), they say, are doomed to failure.
Back in the 90's they were said to be bullet proof and easy to care for. Mine usually lasted about 2 years but didn't noticeably grow in that period of time. Alkalinity and calcium supplementation was not widespread at the time. Buy the right one, care for it well, and you can expect great growth of both the skeleton and the tissue. They need to be on the sand bed, away from sharp rocks that can cut them, with plenty of room to expand and have only a moderate current stirring them. That's their natural habitat.