The bull was one of the most popular zoomorphic motifs that dominated Mesopotamian glyphic art, whether this was a simple representation of the animal or a more elaborate astral figure with wings. The numerous depictions on Sassanian seals attests to the close relationship between Sassanian and Mesopotamian glyptic practices. The depiction was one associated not only with religion, connected to various gods and figures, but also to economic and social values. The bull was an important commodity for the Iranian people, relied upon for food, cultivating the land and for sacrificial purposes. Within the religious sphere, bulls were closely associated with fertility, and the god Dumuzid throughout ancient Mesopotamian art history. This composition of an abstract bull and an astral sign (the inclusion of wings), might also have been derived from the human-headed bull, Lamassu. The figure was an Assyrian protective deity, known as a celestial being and a royal guardian.
For more about stamp seals, see our relevant blog post: Making their Mark