Stichodactyla gigantea or Stichodactyla mertensii?

[mitchelljared]

So figured since I had some time, I'd clear this confusion up for myself by throwing the question to y'all: I've always wondered whether my carpet anemone was a gigantea or a mertensii? The pic is below. My rationale: Must be gigantea because it's hosting two percula clowns, which mertensii does not. However, has settled on a rock groove, and mertensii likes hard substrate, while gigantea likes sand. Could it be a gigantea who just like the hard rock? I know there are always exceptions to most marine rules. Any ideas?