A few years ago I was able to get a three vol. set of Corals of the World, Vol. 1, 2, 3 (in Slip Cover). Every coral known is pictured and discussed in this set . This is an excellent resource that explains the structure and origin of all known corals in all our oceans. I see now that the price has tripled since I purchased them, but if anyone can get their hands on a set “ they are a must have” and well worth it. Here is one link to the set.