Why do we keep Euphyllia and Hydnophora?

[Lampshade]

I"ll have to take pictures tonight of my chalice vs. hammer showdown going on in my tank. It's crazy because they are both frag size, and are 4-5" apart. They can sting eachother's bases no problem, i can't believe the chalice has that much reach! Anyways, they look good, and both have been growing great as competition? I'll be moving them apart a bit soon, worried about everything else around them after this though.