a long spiraling shell (see Molina); we know from an example of a necklace made of seven of these shells that is is not a large as a conch, which was used for trumpeting
Alonso de Molina:
cuechtli. cierto caracol largo. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 25v. col. 1. Thanks to Joe Campbell for providing the transcription.