Porites compressa is generally pale brown or grey. In shallow water it resembles a knobbly boulder but in deeper water it is more columnar. The branches are cylindrical and often fuse together. The growth rate is slow but it often grows into large colonies which may be up to 1000 years old. It is a zooxanthellate coral, having symbiotic unicellular zooxanthellae in the tissues which provide it with energy.
Porites compressa occurs in the Indo-Pacific region, the Red Sea and East African coast. Around Hawaii it is common and is found on reefs and in lagoons to a depth of where the water is relatively undisturbed. In Kaneohe Bay it is the dominant coral species and sometimes forms monospecific stands.