The Stone Spheres of Costa Rica are a collection of over 300 mysterious stone spheres, ranging in size from a few centimeters to over two meters in diameter. They are located in the Diquís Delta region of Costa Rica, and are believed to have been created by the pre-Columbian
From Wikipedia
The stone spheres of Costa Rica 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. The spheres are commonly attributed to the extinct Diquís culture, and they are sometimes referred to as the Diquís spheres. They are the best-known stone sculptures of the Isthmo-Colombian area.