The term patera is commonly used in Venice and has a diffusion in the neighbouring territories like Veneto, Friuli and Istria. As Alberto Rizzi writes in the book Scultura esterna a Venezia, the term is not employed in the sense given to it in classical archaeology, where the patera (πατέρα) is the round vessel, low and wide, used for the sacrificial libations. It instead indicates the Veneto-Byzantines circular bas-reliefs on the facades of the most antique venetian palaces and also in church architectures, like the Basilica di San Marco.

Most all of them date from the end of 12^th century to the 13^th century and fell into disuse at the end of 400. Many imitations were later produced in the 19^th and 20^th century. As Ruskin writes: “The number of these sculptures […] is truly enormous, but although they are scattered all over Venice, it is rare to find them in their original location. When Byzantine palaces were destroyed, sculptures were preserved and inserted into the walls of new buildings with a more or less careful eye for symmetry.”, this is why they are called “erratic sculptures”. Therefore, it’s not easy to give a precise dating to each patera, the chronological assumptions are based on material and style.

The recurring subjects of these artifacts are “groups of birds or animals, now depicted facing each other, separated by an arborean trunk or a column, now in the act of tearing or devouring each other.” The attempts to interpret this iconography so far has not been satisfactory, as a matter of fact, there are barely any sources that can assist the iconographic interpretation of the patere and up to now they have been considered merely decorative or with an allegoric meaning, often deemed to be the fight between virtues and vices.