The clay balls, often called “envelopes”, excavated in the 1960s, were made about 200 years before writing was invented.
The balls were sealed and contain tokens in a variety of geometric shapes, varying from golf ball-size to baseball-size.
Researchers used high-resolution CT scans and 3D modelling to look inside more than 20 examples that were excavated at the site of Choga Mish, in western Iran, in the late 1960s, ‘LiveScience’ reported.
The clay balls were created about 5,500 years ago at a time when early cities were flourishing in Mesopotamia.
The clay balls may represent the world’s “very first data storage system,” said Christopher Woods, a professor at the University of Chicago’s Oriental Institute, in a lecture at Toronto’s Royal Ontario Museum.