Doomira is inspired, clearly, by Japanese mirrors (I saw one, believed to have belonged to Amaterasu, the Sun Goddess). There is a story about a town collecting mirrors from the local women to create a bell. One woman reluctantly gave hers, but, it was passed down through her family. The bell became cursed, because the woman did not give the mirror over with good intentions. That explains a mirror turning into a bell. And, if you have seen any bells of the period, they do look like this. It resembels a dogu, somewhat, and that is what Claydol was based on. There might be aztec influence, but, it's barely there. The Japanese began metallurgy around AD 300 long before the Aztec existed.
DotakuJapanese bells that Dookatun are based off. (link goes to a GIS)