Originally Posted by
KrakHed
Yes, except for the fact that Gronn are literally descendants of creatures of stone. They might not be literal rocks, but they're clearly meant to be reminiscent of them. And they're features that other Earth-related creatures, like Drogbar, tend to possess. They're stone-like, even if not actual stone.
That makes it likely that Trolls, who are associated as creatures of stone in our own mythology, are Earth-related. Other than that, they also have similar features to Djinn. So Elemental ancestry doesn't seem so odd to me.