The traditional stone wheel used to crush cooked agave in tequila production is called a tahona.
After agave piñas are cooked, a large wheel made traditionally from volcanic stone rolls over them to break down the fibers and release juice and cooked plant material. The resulting mixture can then be fermented and distilled.
Tahona milling is labor-intensive and relatively slow compared with modern mechanical shredders or diffusers. Some producers retain it because it is historically significant and because the resulting fiber-rich material contributes a distinctive character to certain tequilas.
The term is often confused with “horno,” the oven used earlier in the process. A tahona performs crushing, while a coa harvests the agave and an alambique is a still used for distillation.