Mackay continues (p. 377 in Marshall 1931): "The boss was then carefully rounded off after the groove that always runs across its centre had been roughly made by a V-shaped cut.
Unicorn (so-called) motif in the ancient Indus Valley.
Mackay writes that most of the bosses on the backs of seals had the same size and shape. The perforation always runs in the direction of the animal's body, to help keep the seal upright when worn around the neck. The boss is centered on the back and
If the figure does represent a cattle species, the clearly carved collar, garland and necklace could help explain its function. Sacrificial animals in village India are often garlanded and decorated similarly today.
This unicorn seal was also discovered during the late 1927-31 excavations at Mohenjo-daro. One theory holds that the bull actually has two horns, but that these have been stylized to one because of the complexity of depicting three dimensions.
In addition to any commercial functions, the seal may also have designated a position of authority. The motif on the seal could also have been an amulet or charm. The seal itself was probably worn around the neck, with a chord passed through the boss
[Original text] "The animal most often represented on the seals is the apparently single-horned beast . . .. There is a possibility, I think, that the artist intended to represent one horn behind the other.