A device for impressing characteristic marks into a soft surface, such as wet clay or wax, to indicate ownership or authenticity. Seals were made of bone, ivory, stone, or wood and had an intaglio design and were in the form of stamps or cylinder seals. The first can have a very wide range of shapes, and gives single impressions. The second, characteristic of ancient Mesopotamia, is rolled across the surface to yield a frieze of repeat designs. Their social and linguistic significance is great. They were fundamental in the development of writing system and were a status symbol of authority and sometimes accorded talismanic properties. The use of seals and writing on clay tablets appeared together in Mesopotamia, towards end of 4th millennium BC.