CYLINDER SEAL: A cylinder engraved with a design, scene, and/or inscription which was impressed onto the plastic clay when the cylinder seal was rolled over a clay tablet. This was the standard seal form of the Mesopotamian civilization, starting in the Uruk period. The incised stone cylinder was rolled over a soft surface so that the design appeared in relief. These seals were used to mark property and to legalize documents. Dating is based on changes in the design carved on the seal as well as the seal’s size and proportion.