Perfect Petrospheres: The Manufacturing Mystery of Pre-Columbian Costa Rica

Deep in the jungles of Costa Rica lie over three hundred perfectly round spheres of solid granodiorite. Ranging from a few inches to over two meters in diameter and weighing up to fifteen tons, the Diquis Spheres are an absolute geometrical and archaeological anomaly. How did a pre-Columbian civilization, possessing no metal tools or wheels, carve volcanic rock into spheres of such astonishing m...