I only know about Bison through the movies and of course, post like yours. I think some countries likes using animal representation in their currency and other stuff, for Nigeria, it's actually eagle.
Why is the gold colored currency costlier than the plain or silver one?
These notes are actually made with real gold, so there's one gram of pure gold embedded in the note itself. The investment is in the gold and the art I suppose as well. They do make some embedded with silver as well, but I like silver coins more personally. This is just a less expensive way to invest in gold, buying a gram or half a gram is much more practical for most people, and ounce would cost you $2,666 at the moment!