chiyahuitl (Chav1)
This element of a marsh or swamp (chiyahuitl) has been carved from the compound Chiyauhtzinco, a barrio of Huexotzinco. If it had not come from the compound, it probably would have had a rounder shape. This sign shows swirling water in both circular and rectangular (or stepped fret, xicalcoliuhqui) shapes. Tiny droplets appear occasionally around the perimeter. Tiny lines coming off the main body seem to suggest tules or cattails, plants that might be found in a marsh or swampy area.
Stephanie Wood
1578
Stephanie Wood

chiyahu(itl), a swamp or a marsh, https://nahuatl.wired-humanities.org/content/chiyahuitl
xicalcoliuhqui, stepped fret coil, https://nahuatl.wired-humanities.org/content/xicalcoliuhqui
The Codex Chavero of Huexotzinco (or Códice Chavero de Huexotzinco), https://www.loc.gov/resource/gdcwdl.wdl_03246_001/?sp=1
The Codex Chavero of Huexotzinco (or Códice Chavero de Huexotzinco) is held by the Instituto Nacional de Antropología e Historia, México. It is published online by the World Digital Library and the Library of Congress, which is “unaware of any copyright or other restrictions in the World Digital Library Collection.”