I've discovered another piece of the prehistoric puzzle: some kind of tool! It looks like a prehistoric multitool or such, according to that little part on the right of the object. It could be an acient lighter! Here's how it might work: Two of these objects get a connection, probably using friction, to start a fire. They probably have a social function: If two people start a fire with their 'cards', it might symbolise harmony of the groups. So 'Nintendo' turns out to be a social god!