Hmmm...if he's calling it a danae, it might not be a plating "cap" type of coral but rather an encruster. If it doesn't plate, it looks quite a bit like a "morning star" encrusting montipora. It really doesn't look like a danae to me, as it lacks the dome shaped verrucae.
I suspect the morning star montipora might be M. nodosa, or M. mollis.
Now I just noticed that you said it did plate up, so it's probably not the same as the morning star.
I have something similar that has a greenish cast under actinics, with bright green polyps, but looks purple-brown under intense light.
Looking forward to more pics of yours. Great looking coral
-Tim