Hundreds of mysterious spheres are discovered beneath the Temple of the Feathered Serpent, in the pre-Hispanic city of Teotihuacan, just 30 miles from Mexico City.
Also known as the Temple of Quetzalcoatl, this six-level step pyramid is decorated with feathered serpent heads and snake-like creatures. It was built by the Teotihuacan people possibly between 100 and 200 A.D.
The excavation focused on a 330-foot-long tunnel which runs under the structure. The conduit was discovered in 2003 when heavy rain uncovered a hole a few feet from the temple.
Exploration of the tunnel, which was deliberately filled by debris and ruins by the Teotihuacan people, required several years of preliminary work and planning. A few months ago archaeologists found two side chambers near the entrance.
The walls and ceiling of both chambers were covered with a mineral powder composed of magnetite, pyrite and hematite which provided a special brightness to the place and a peculiar atmosphere for the rituals that were most likely carried there.
According to archaeologists, the spheres would have appeared metallic to those who placed them here.
To understand where and how the tunnel ended, the archaeologists used a 3-foot-long, remote-controlled robot which was able to explore the last part of the duct.
Called Tlaloc II-TC, the robot uses an infrared camera and a laser scanner to generate 3D visualization of the spaces beneath the temple.
The chambers are displayed as they were plotted by the laser scanner.
The archaeologists will next explore the last part of the tunnel and the three chambers seen through the robot cameras. They believe it's possible the central chamber at the end of the tunnel contains the remains of those who ruled Teotihuacan.