The Harappan seal in the Edward Gans Collection (Phoebe A. Hearst Museum of Anthropology, University of California at Berkeley, Slide 1) is a classic fired white steatite square Harappan seal of 29mm x 29mm. The unicorn motif and the square shape are predominant features of Harappan seals, the carving is finely executed and the seal is well preserved. During the Mohenjo-daro excavations of 1927-1931, in which this seal was unearthed, 388 unicorn seals were found (Mackay 1938). Mackay suggested that the artist may have been trying to portray one horn behind the other, but due to the craftsman's limited skills at depicting perspective, only one horn was indicated. This convention is seen on archaic Sumerian seals as well. Previous to Mackay, Marshall, in his 1922-1927 expeditions at Mohenjo-Daro, found a total of 558 seals (Marshall 1931). All were similar to this one with only one or two lines of "pictographs" and a single animal motif. Most of these were square or rectangular with a perforated boss on the back. Almost all of the square seals were made of steatite but the thickness of the seal varied greatly. A wide variety of other inscribed objects were found at Mohenjo-daro, some of which were intaglio seals, while other items were inscribed tablets or tokens. The shapes of these small objects include cylinders, squares with perforated boss, squares with no boss and tablets or tokens frequently inscribed on both sides, rectangular tablets without a boss, button seals with linear or geometric designs, rectangular with perforated backs, incised cubes, circular with perforated bosses, rectangular with perforated bosses and circular without bosses but inscribed on both sides.
While many people focus on the aesthetic qualities of these inscribed objects, we must remember that these were also functional objects. The seals appear to have been used extensively in both internal and external trade (map).
Numerous impressions of seals have been found