Appropriate, since they are "the primitives", after all. They'll stare at it, turn it over and over in their hands, pass it around the campfire, bash Tonga in the head with it, finally have a breakthrough in recognizing it could be a tool to perform work with, and promptly toss it into the bushes in fear.
In a few millenia, they might even find a round stone disc with a hole in its center, and ponder what it might be used for.