'Lithic spheroids' (stone balls) are small man-made Stone Age artefacts (dating from around 1.8 million years ago to 70,000 years ago). They have mainly been found in Africa, but also in Europe and Asia. Exactly how and why they were made remains uncertain.

Stone balls are present in some Oldowan and Acheulian stone-tool assemblages, the oldest human cultural complexes known to humankind, dating to around 1.5 million years old. Their presence has puzzled researchers for more than half a century and still, little is known about how and why they acquired this shape, or what their uses might have been. Although some in the scientific community believe that these tools, known as spheroids, were intentionally manufactured, others claim that their form was obtained accidentally through percussion activities. In addition, some researchers have proposed that their morphology must reflect a specific function, or perhaps even some kind of social or symbolic norm."

Source : IPHES news (march 2020)

IPHES ( Institut Català de Paleoecologia Humana i Evolució Social) runs the Lower Paleolithic Spheroids Project (LPSP), aiming to understand the origins and purposes of the stone balls.

As mentioned in the quote above, one theory is that they became rounded as a result of their repeated use as 'hammers'.

But a recent (2023) research project from the Hebrew University of Jerusalem (HUJI), which used 3-D curvature analysis techniques to scan sample stones, suggests instead that they were deliberately made by a 'knapping' process - i.e. by repeated chipping with another stone tool.

Spheroids are one of the least understood lithic items yet are one of the most enduring, spanning from the Oldowan to the Middle Palaeolithic. Why and how they were made remains highly debated.

Source :Royal Society Open Science, Volume 10, Issue 9

The purpose for their manufacture, however, remains unknown. One possibility is that they were intended as weapons - .e.g. sling-shots. Others suggest their use for food pounding.

Also see: Diquis spheresplugin-autotooltip__plain plugin-autotooltip_bigDiquis spheres

In the 1930's workers from the United Fruit Company, who were clearing land in the Diquís Valley Delta region of Costa Rica, began finding large numbers of almost perfectly round stone spheres.

The spheres, which range from a few kilograms up to around 16 tonnes, are accurately made, presumably by chipping. and Carved stone balls (Bronze Age)plugin-autotooltip__plain plugin-autotooltip_bigCarved stone balls (Scotland)

More than 400 examples of Scottish Carved Stone Balls have been found. They are believed to have originated in the late Neolithic and the Bronze Age - i.e. thought to be more than 5,000 years old.

Most have been found in north-east Scotland, mainly Aberdeenshire. They usually range in size from 70 to 90mm diameter, and are hand-carved with varying numbers of symmetrically-arranged protruding bumps on the surface (from 3 to over 150) .