Deco Metal Mystery

I found this several years ago, probably at a thrift store. It has a definite Art Deco look to it but I cannot figure out what it is! Can anyone help? Made of metal, non-magnetic. The top looks like copper and the underside has a black coating. It's about 10-1/2" inch along each side of the "triangle". There is a lip on the underside which makes me believe it fit over something--a casserole or a radio or clock?? Each of the 3 sides has a small hole for a screw or nail and also a larger opening. Each "corner" is almost identical except one has a larger, sort of half-moon shape while the other two corners have round ones. I'm crossing my fingers that someone will recognize this piece or will have a good guess. Thanks!