The exact use of pieces of this type is not known, and they have been variously described as a coin, charm or file. A number of these implements have been published: by d'Argencé, The Hans Popper Collection of Oriental Art, Japan, 1973, no. 25; and by Paul Singer, "Some Puzzle Pieces", Oriental Art, Vol. XVIII, No. 2, Summer 1972, pp. 155-62. The author illustrates several, including one from his collection, p. 159, figs. 7-8, which is very similar to the present example, and another p. 158, fig. J, which had been found inside a bronze rhinoceros-form vessel excavated in Shanxi province, fig. 10, suggesting that these pieces may have been files used to grind or grate rhinoceros horns for medicinal purposes.