thanks jps!
what i think i like best about that photo is that it shows how they grow in the wild. you can see they are growing on dead seriatopora (birdsnest coral). the polyps are sparse, usually only one or two growing together, and mixed with a variety of other polyps in the bunch. these don't grow in thick mats on rocks in the wild like you see with a lot of other z's/p's. and being that they grow on dead birdsnest, it is indicative of the environment they most likely prefer - high light/high current, such as a reef crest zone.