In Aztec religion, Xiuhcoatl was a mythological serpent, it was regarded as the spirit form of Xiuhtecuhtli, the Aztec fire deity, and was also an atlatl wielded by Huitzilopochtli. Xiuhcoatl is a Classical Nahuatl word that literally translates as "turquoise serpent"; it also carries the symbolic and descriptive meaning, "fire serpent".
Xiuhcoatl was a common subject of Aztec art, including illustrations in Aztec codices and its use as a back ornament on representations of both Xiuhtecuhtlu and Huitzilopochtli. Xiuhcoatl is interpreted as the embodiment of the dry season and was the weapon of the sun. The royal diadem (or xiuhuitzolli, "pointed turquoise thing") of the Aztec emperors apparently represented the tail of the Xiuhcoatl, the fire serpent.
Read more about Xiuhcoatl: Attributes, Mythology, Ritual