In the ancient Mesopotamian and Indus Valley civilizations, a small, cylindrical stone incised with a figural scene, design, and/or inscription. When the seal was rolled across wet clay or wax, the resulting raised image served as a mark of ownership or an authenticating signature. Web resources  here and here. Videos here and here.

Cylinder seal. From Ur (Tell el-Muqayyar, Iraq). Jadeite. Akkadian. Ca. 2350–2150 BCE. Penn Museum, Philadelphia.