Cuauhxicalli

The eagle form of many cuauhxicalli was not decorative choice but doctrine carved in stone. Aztec belief held that the sun required constant nourishment of human blood and hearts to keep moving across the sky and beginning each new day, and that warriors who died in battle or on the sacrificial stone joined the sun's daily procession as its escort, imagined as a flock of eagles and hummingbirds accompanying the solar disk from dawn to noon. A cuauhxicalli carved as an eagle therefore depicted the very transformation its contents were meant to enact: the heart placed in the hollow of the eagle's back was, in the ritual logic, delivered directly into the sun's retinue rather than merely presented as an offering from a distance.

Some cuauhxicalli instead take the form of an undecorated stone box or basin, and archaeologists have recovered both types from Templo Mayor excavations, distinguished as much by find context, close to the summit shrine of Huitzilopochtli, as by their exterior form. Smaller portable cuauhxicalli, carved to the same eagle design but sized for a lesser shrine, are also known from the archaeological record, suggesting the form was replicated at a scale below the state temple as well as at Tenochtitlan's own summit.

Cuauhxicalli were positioned with deliberate precision, generally atop or immediately beside the twin shrines crowning the Templo Mayor, so the heart removed at the summit could be placed in the vessel within the same continuous ritual sequence rather than carried elsewhere afterward. Eduardo Matos Moctezuma's excavations of the Templo Mayor precinct, beginning in 1978, recovered several cuauhxicalli in or near their original ceremonial positions, allowing modern archaeology to confirm details colonial era chroniclers had described from secondhand or eyewitness account.

Some surviving examples carry extensive carved imagery beyond the eagle or basin form itself, calendrical dates, images of rulers and conquered polities, and cosmological scenes that root a single vessel's ritual function within the wider Aztec claim to divinely sanctioned imperial rule, in the same manner as the carved temalacatl monuments from the same precinct. Together the cuauhxicalli and the temalacatl represent the two principal stone furnishings of Aztec blood sacrifice recovered archaeologically, one receiving the offering and one staging the combat that sometimes produced it. Comparative study of surviving cuauhxicalli against contemporary codex illustrations lets researchers cross check which carved forms depicted in painted sources actually correspond to physical objects that have survived, rather than to artistic convention alone.