While varying in specific morphology, metates are typically made of a large stone with a smooth depression or bowl worn into the upper surface. Materials are ground on the metate using a smooth hand-held stone known as a "mano" or "metlapil". This action consists of a horizontal grinding motion that differs from the vertical crushing motion used in a mortar and pestle. The depth of the bowl varies, though they are typically not deeper than those of a mortar; deeper metate bowls indicate either a longer period of use or greater degree of activity (i.e., economic specialization).