Snuff trays are conspicuous objects that are found in archaeological contexts throughout Andean South America. At San Pedro de Atacama, in northern Chile, snuff trays that exhibit iconographic motifs similar to those found on Tiwanaku megalithic monuments have been assigned to the Tiwanaku style. In the present work, we propose a new definition for this style based on the occurrence of three morphological features: an overall trapezoidal shape, incurving sides, and sharp top corners. This group includes trays with iconography from the previously defined Tiwanaku style, as well as other trays without iconography. Principal component analysis shows that Tiwanaku-style trays with and without iconography make up a single group that is significantly different from plain, largely rectangular San Pedro-style trays. The relative proportion of Tiwanaku-style trays with and without iconography does not differ between cultural periods and archaeological sites. The results point to shape as an important trait for assigning trays to styles. Furthermore, the results show that during the Middle period four main types of snuff trays were in use: Tiwanaku trays with and without iconography and local San Pedro trays, also with and without iconography. We explore the possible social implications of this co-occurrence of styles.