Granite carving of a serpent

The serpent played a very important role in Mexica religion and was represented in a variety of forms. Many superb examples, carved in stone, have survived. Some were very realistic, while others were blended with fantastic elements, as in representations of Xiuhcoatl, the Fire Serpent. The Plumed Serpent, Quetzalcoatl, is also frequently depicted. The majority of the serpents represented in Aztec sculpture are rattlesnakes. This is one of the finer surviving examples, accurately depicting many important anatomical details, including the fangs and bifurcated tongue. The thirteen segments of the tail can be clearly distinguished, one for each year in the life of the serpent, since a new rattle is formed when it sheds its skin. Traces of red pigment remain. Thirteen was a significant number among the Mexica, related to their concept of the world. The Mexica universe was organized in three levels: a celestial realm, a terrestrial one, and the underworld. There were thirteen levels in the celestial realm, each one inhabited by different gods. In the Mexica sacred calendar (of 260 days) there was a 20-day cycle that was combined with thirteen numbers. The same combination ( for example, 1 Alligator) did not repeat itself until the full cycle of 260 days was completed. *The people and culture we know as 'Aztec' referred to themselves as the Mexica (pronounced Me-shee-ka).