The Perfect Stone Spheres a Banana Company Found by Accident

2026-08-15 · Impossible Objects · 7 min read

In the 1930s the United Fruit Company was cutting new banana plantations out of the forest of the Diquis Delta, in the Pacific lowlands of southern Costa Rica. Crews with machetes, fire and heavy machinery pushed into ground that had not been cleared in centuries. What came out of it was not expected. Half buried in the earth, scattered through the delta of the Terraba and Sierpe rivers and out on the offshore Isla del Cano, were stone balls. Not roughly rounded boulders, but spheres, worked to a curvature so even that a hand run across the surface finds almost nothing to catch on.

They came in every size. The smallest are only a few centimetres across and can be held in one hand. The largest recorded example measures about 2.57 metres in diameter, taller than the men who found it, with weight estimates running from roughly 15 tonnes upward depending on the stone and the source consulted. More than three hundred are known, and the true original number was certainly higher. Most were carved from a hard, dark igneous rock described in the literature as gabbro or granodiorite; about a dozen each are known in shell-rich limestone and in sandstone. The igneous stone does not occur where the spheres were found. It had to be brought from hills several kilometres away, across broken country and river channels, without wheels and without draft animals.

Reader comments (0)