A brainchild of Sumerian Bureaucracy

That is what this well written article on Sumerian writing and seals calls these wonderful objects, engraved with a picture story and accompanying text written with cuneiform. Their function was to roll an impression onto a two-dimensional surface, generally wet clay. Cylinder seals were invented around 3500 BC in Mesopotamia. They were used as administrative tools, as jewelery/magical amulets and also to notarize or attest to multiple impressions of clay documents.

One of the best image repositories for cylinder seals is on wikimedia commons and another very nice collection can be seen on the page of the Schoyen Collection.

The image below shows a number of cylinder seals from the collection of the Papiermuseum in Basel, Switzerland.