This image of the youthful, beardless Christ, shown as the Good Shepherd is one of the oldest depictions of Christ beardless.
The mosaic is in the lunette over the entrance door of Galla Placidia, and difficult to see due to the backlight from the door.
Christ is shown seated with the lambs on either side, as opposed to the "good shepherd" images from pagan art
that showi the "sheep bearer" with the lamb over the shepherd's shoulder.
This image also shows the starry sky which forms a mosaic background on the barrel vaults for other imagery in the mausoleum.
The mosaics dates from 425-450.