A reliquary of the late 14th century shows a crystal cylinder where the relics are displayed.  The small-scale image attempts to reference real-life.  Four abbots, with their crosiers, carry the crystal cylinder as if they were supporting the presentation of relics in a procession through a city's streets.  See reliquary carried in procession in the Tres Riches Heures manuscript, 1413-16, (Viollet-le-Duc, Mobilier 1:227) back to "worship"