Hundreds Of Mysterious Spheres Discovered By Robot In Ancient Temple [VIDEO]

The discovery of hundreds of strange orbs in an ancient temple near Mexico City has researchers mystified.

Archaeologists discovered the strange spheres using a robot to explore the Temple of the Feathered Serpent, also known as the Temple of Quetzalcoatl. The structure is a six-level pyramid decorated with snake-like creatures. It is considered one of the most important buildings in pre-Hispanic city of Teotihuacan.

"They look like yellow spheres, but we do not know their meaning. It's an unprecedented discovery," said Jorge Zavala, an archaeologist at Mexico's National Anthropology and History Institute, according to Discovery News.

Researchers focused their excavation on a 330-foot long tunnel that runs beneath the temple; it was discovered in 2003 after heavy rainfall uncovered its entrance.

The tunnel has several chambers and using the robot, researchers were able to explore chambers that had not been excavated yet. One of the robot's designers said the tunnel is "in pristine condition, untouched for almost two millennia."

Hundreds of spheres lay in rest in the tunnel's north and south chambers. Sized from 1.5 inches to 5 inches, the spheres have a clay core and are covered with a yellow material called jarosite.

"This material is formed by the oxidation of pyrite, which is a metallic ore," Gómez Chávez said to Discovery News. "It means that in pre-Hispanic times they appeared as if they were metallic spheres. There are hundreds of these in the south chamber."

When they were new, the spheres would have glistened in the light.

"Pyrite was certainly used by the Teotihuacanos and other ancient Mesoamerican societies," George Cowgill, professor emeritus at Arizona State University and the author of several publications on Teotihuacan, told Discovery News. "Originally the spheres would have shown brilliantly. They are indeed unique, but I have no idea what they mean."