Spheroids, also known as stone balls, polyhedrons, or bolas, are amongst the oldest surviving lithic tool types, appearing as early as the Oldowan and continuing into the Middle Palaeolithic.
However, their purpose and manufacturing process have long been debated. Previous studies were limited by small sample sizes and subjective classification schemes.
To overcome these issues, the researchers introduced novel quantitative techniques, including edge angle measurement, centre of mass calculation, surface curvature analysis, and crucially, spherical harmonics analysis.