A curling stone moves in a way that you wouldn't expect if you were just looking at really basic physics, right? So the base of a curling stone is not flat. It's actually concave and there's only a very narrow ring. And these stones are garnished. They're made from a really particular garnish from one place in Scotland. The fundamental understanding of what's happening where that kind of rough granite surface is touching the rough pebbled ice is still up for debate.