In many ancient and more recent societies, seals have been used for imprinting an image on a document or a product. Such seals have been among the most numerous artifacts found in the Indus Valley cities. They often carried the image of an animal—a bull, an elephant, a crocodile, a buffalo, or even a mythic creature such as a unicorn—as well as a title or inscription in a still undeciphered script. Thus the seals were accessible to an illiterate worker loading goods on a boat as well as to literate merchants or officials. Particular seals may well have represented a specific clan, a high official, a particular business, or a prominent individual. Unicorn seals have been the most numerous finds and were often used to make impressions on clay tags attached to bundled goods, suggesting that their owners were involved in trade or commerce. Because bull seals, such as that shown in Visual Source 2.1, were rarer, their owners may have been high-ranking officials or members of a particularly powerful clan. The bull, speculates archeologist Jonathan Kenoyer, “may symbolize the leader of the herd, whose strength and virility protects the herd and ensures the procreation of the species, or it may stand for a sacrificial animal.”30 Indus Valley seals, as well as pottery, have been found in Mesopotamia, indicating an established trade between these two First Civilizations.