One of the strangest mysteries in archaeology was discovered in the Diquis Delta of Costa Rica. In the 1930s, the United Fruit Company planted huge quantities of bananas in this region. Workers clearing forests found numerous spherical stones. The balls were perfectly round and were anywhere from a few inches to over 8 feet in diameter. They were composed of solid granodiorite; a very hard igneous rock. The mysterious balls were cut, trimmed and then polished to a high luster.