bread mold or of something similar (see Molina)
ixpuxcauiliztli. moho de pan, ode cosa semejante. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 47r. col. 1. Thanks to Joe Campbell for providing the transcription.