Coober Pedy is a town that exists only because it sits on the world’s largest source of opals. As you drive into town, each side of the highway is flanked by thousands, maybe hundreds of thousands of pyramid-shaped piles of dirt. They’re created when opal miners drill 80-feet deep round holes straight down into the earth. After digging out any opals they find, the miners abandon the the holes, leave the piles of dirt behind and and move on to dig new holes nearby. Kind of bizarre, isn’t it?