One of the strangest mysteries in archaeology was discovered in the Diquis Delta of Costa Rica. Since the 1930s, hundreds of stone balls have been documented, ranging in size from a few inches to over six feet in diameter. Some weigh 16 tons. Almost all of them are made of granodiorite, a hard, igneous stone. These objects are monolithic sculptures made by human hands.
They were originally found in the delta of the Térraba River, also known as the Sierpe, Diquís, and General River, near the towns of Palmar Sur and Palmar Norte. Balls are known from as far north as the Estrella Valley and as far south as the mouth of the Coto Colorado River.
They have been found near Golfito and on the Isla del Caño. Since the time of their discovery in the 1940s, these objects have been prized as lawn ornaments. They were transported, primarily by rail, all over Costa Rica. They are now found throughout the country.
There are two balls on display to the public in the U.S. One is in the museum of the National Geographic Society in Washington, D.C. The other is in a courtyard near the Peabody Museum of Archaeology and Ethnography, at Harvard University in Cambridge, Massachusetts.
Since their discovery in 1940, the vast majority of these balls have been removed from their archaeological contexts to serve as lawn ornaments across Costa Rica. Many of the balls studied by Lothrop appeared to have rolled off of nearby mounds.
Several had been covered by layers of fine silt, apparently from flood deposits and natural erosion. Naturally, they are “out of context” in the sense of having few good archaeological associations.