On the floor, between the piers and the podia, is a black-and-white mosaic. It contains a marble threshold at the point where the podia begin. There are five depictions, from south to north:
- A naked man, holding a pruning knife and some sort of shovel. A few white tesserae suggest that the latter object is perforated. A similar symbol is found in the Mithraeum of Felicissimus, where it refers to the grade Leo. It was used to carry fire. The hair of the naked man may be the lion's mane. But in the Mithraeum of Felicissimus the knife refers to the grade Perses.