They are an interesting geological formation of perfect spheres, which due to their large size are considered unique worldwide. They are so perfect that when they were found in the mid-20th century, they were thought to be primitive sculptures.

Since then several theories have been postulated. The University of Guadalajara indicates that they are the result of lava that arose from an explosion millions of years ago and that the rocks formed as they drained and rolled. 

These voluminous rocks measure more than three meters in diameter and according to scholars are the result of the crystallization of volcanic ash, which precipitated in the Sierra de Ameca from the Tequila Volcano approximately 40 million years ago.

The rocks are located within a forest of oaks, the habitat of 94 species of birds, 16 species of large mammals and 17 of amphibians and reptiles, within the municipality of Ahualulco de Mercado.

There are trails that take you along a 6 km route, where you will not only be able to observe the amazing formations, but also the rich flora and fauna of the region. Additionally, there are several viewpoints from where you have beautiful panoramic views.

In addition, archaeological remains have been found.