 So, when people think of rocks and minerals and works of art, you might generally just think of works that are in museums, objects in cases, or large pieces of sculpture, but something else that you can consider are works of architecture. And in this orientation, one of the case studies that I'm going to present is for the dome of the pantheon, which relies on a whole group of rocks and minerals for its construction. It's made up of seven different layers of concrete in the dome. And each one has fillers in that Roman concrete of differing density. And those really affect the performance of that dome as an architectural form. So that's something else that you can consider when you're coming up with a project is something that might be a little bit out there that might not be as obvious to find when you're just searching a museum website.