On the reverse of the cross and through the examination with infrared reflectography, has revealed the anatomy of the head of another lamb, just below of the visible Lamb, the circle of its halo, the fragment of a front leg and a cross.
All underlying drawings are slightly displaced to the left, and, concretely, the cross is placed closer to the edge of the circle. In fact, the mentioned underlying drawings are located just below the blue lapis lazuli, a pigment with a high reflectance and not much absorption of the infrared radiation.