These ancient stone spheres are an assortment of over 300 petrospheres in Costa Rica, on the Diquís Delta and on Isla del Caño. Locally, they are also known as bolas de piedra (literally stone balls). The spheres are commonly attributed to the extinct Diquís culture, and they are sometimes referred to as the Diquís Spheres.
In the 1930s, the United Fruit Company was clearing land in the Diquís Valley of Costa Rica, when workers began unearthing large numbers of almost perfectly round stone spheres. Spheres range in size from a few centimeters to over 2 meters in diameter and weigh up to 15 tons. No one actually knows why they were made. There are many theories but little proof. Some believe they denoted rank or kingship, others think they were merely status symbols or perhaps tribe symbols.
Spheres range in size from a few centimeters to over 2 meters in diameter and weigh up to 15 tons
According to University of Kansas archeologist John Hoopes, “The balls were most likely made by reducing round boulders to a spherical shape through a combination of controlled fracture, pecking, and grinding.” They were likely produced by an extinct civilization of people that existed in the area in the Aguas Buenas Period (300–800 CE) and Chiriquí Period (800–1550 CE). Their culture disappeared after the Spanish conquest.
The only method available for dating the carved stones would be stratigraphy, but most stones are no longer in their original locations
Many myths surround the stones, including ones that claim they came from Atlantis or were made as such by nature. In the Bribri cosmogony, which is shared by the Cabecares and other American ancestral groups, the stone spheres are “Tara’s cannon balls”. According to legend, Tara or Tlatchque, the god of thunder, used a giant blowpipe to shoot the balls at the Serkes, gods of winds and hurricanes, in order to drive them out of these lands.
Also, there have been many claims that the spheres are perfect, or near-perfect in roundness, although some spheres are known to vary over 5 centimeters (2.0 in) in diameter. Also, since the stones have been damaged and eroded over the years, it is impossible to know exactly their original shape.