Watch List notes:

2nd century B.C. Æ unit (17 mm, 4.37 g). 3-headed male deity Mahakal (Shiva) standing facing with indradhvaja-in-railing to right, tree-in-railing to left and river with fish below / Composite symbol with Nandi bull rearing right surrounded by 4 orbs. Pieper -. Very rare and choice. Green patina. Very fine. 

Lord Mahakal (Shiva) is the deity worshipped in Ujjain. The reverse has a very rare 'Ujjain' symbol - a rearing bull in the center playing with four orbs in the four corners.