Native of Numidia, and later widespread since ancient times throughout
the Roman Empire, the guinea fowl appears only in the Archiepiscopal
Chapel. In the arbour of the vestibule it is represented eleven
times and stands out against the miraculous golden background.
The black plumage is vividly rendered with purple, blue and white
tesserae, intended to mimic the small lighter spots that characterise
its appearance. The nuances in the breast are rendered with purple
tesserae. The horn and wattles are outlined by few orange tesserae, cut
 in different dimensions and laid to render the rounded and soft shape.