I have an old "Roman" coin and curious as to its historical standing?

It's made of copper and extremely distressed. The back side, however, is quite clear. In the center it has the Roman numeral "M" with a cross directly above it. On either side of the "M" it has the symbol for both the sun and the moon (crescent). Directly below the "M" there is a what appears to be a triangle with the letters ANTX below that. Any help would be greatly appreciated.