Mesopotamian cylinder seals

Via evencleveland

From the British Museum:

Mesopotamian cylinder seals are small cylinders, generally made of stone and pierced through from end to end so that they could be worn on a string or pin. The surface of the cylinder was carved in intaglio (cut into the stone) with a design, so that when rolled on clay the cylinder would leave a continuous impression of the design, reversed and in relief. Cylinder seals were invented around 3500 BC in southern Mesopotamia (now Iraq) or south-western Iran, and were used as an administrative tool, as jewellery and as magical amulets until around 300 BC.