I tried an experiment a couple of years ago, placing a hammer and a frog up against each other: my lfs has that situation. It finally ended when the two corals began to annoy each other and I moved them about half a foot apart.
Time has redone the deal: they have both doubled in size---the hammer is well over 50 heads, and the frog I have no idea, but I'd say 5-10---it's always too expanded to tell---and are now within 1/2 inch of each other. This time, however, they're not aggressing, nor showing the tendency to do so---[hyper-developed tentacles, mimicry of the other coral type, which they previously showed.] Now they look apt to grow together. I'm going to have to frag the hammer: it's got half my 54 gallon; but it's interesting that these two corals are doing so extremely well in proximity. I have a few popped-head corallettes from a house move situation, and one that I think is hammer has snuggled up right under the frog and stayed there for months.
One often sees sps tanks with a great deal of overlap, but this is certainly a type (euphyllias) that has that potential, allowed to grow at its own pace.
Time has redone the deal: they have both doubled in size---the hammer is well over 50 heads, and the frog I have no idea, but I'd say 5-10---it's always too expanded to tell---and are now within 1/2 inch of each other. This time, however, they're not aggressing, nor showing the tendency to do so---[hyper-developed tentacles, mimicry of the other coral type, which they previously showed.] Now they look apt to grow together. I'm going to have to frag the hammer: it's got half my 54 gallon; but it's interesting that these two corals are doing so extremely well in proximity. I have a few popped-head corallettes from a house move situation, and one that I think is hammer has snuggled up right under the frog and stayed there for months.
One often sees sps tanks with a great deal of overlap, but this is certainly a type (euphyllias) that has that potential, allowed to grow at its own pace.