About the size of a cricket ball, they are precisely fashioned to be within a millimetre of the same size.
This suggests they were meant to be used together in some way rather than individually.
The Scottish stone circles are similar in form to Stonehenge, but contain some much larger stones.
To test the theory, researchers from the University of Exeter constructed a model in which wooden balls were inserted into grooves dug out of timber planks.
When heavy concrete slabs were placed on a platform above the balls, held in position by more grooved tracks, they could be moved with ease.
Archaeologist Andrew Young described the experiment in which he sat on top of the slabs to provide extra weight.
He said: “The true test was when a colleague used his index finger to move me forward – a mere push and the slabs and I shot forward.
“This proved the balls could move large heavy objects and could be a viable explanation of how giant stones were moved.”