The money used by Shang people was shellfish, including seashells, bone shells, stone shells, jade shells and copper shells. The appearance of the copper shell shows that the Shang Dynasty already had metal coins.

The development of business needs a common currency. In Shang Dynasty, China first used coins, besides real shellfish, there were bone shellfish and cast copper shellfish. The appearance of bronze shells indicates that the Shang Dynasty had a metal-cast currency.