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.