ATTICA. Athens. Circa 4th century BC. Kollybos or symbolon (Bronze, 7 mm, 0.35 g, 1 h). Bulbous amphora with high handles. Rev. Φ. For the general type, see Agora XXVI pp. 24-25 and for illustrations of 179 examples (over 600 are known), see Svoronos pl. 18. An unusual and interesting piece, not a coin but a form of token. Very fine.
From the Vineyard Collection, ex Classical Numismatic Group 51, 15 September 1999, 330 (part).
This is actually a very small symbolon (plural: symbola) or token issued to be exchange for various official services or payments. Large examples are well-known to have been used as theater tickets, others would have been given to jurymen and other similar individuals to be exchanged for their daily payments or for food. As noted above, J. Kroll provides a succinct discussion of their function in Agora XXVI, along with full references.