Focus on finds – small clay balls
There have been many puzzling finds over the past 20 years of excavation. Among these are a number of tiny, marble-sized, clay balls that have popped up regularly across the site.
The Ness of Brodgar total currently stands at 31, but these have been recovered at other Neolithic sites in Orkney – including Pool, Sanday; Rinyo, Rousay and Smerquoy, Muckquoy and Stonehall, on the Orkney Mainland. At the latter, 20 examples were found across the site.
Although small, the Ness balls vary in size, with diameters between 13.8mm and 31.8mm. Despite the name, they’re not perfectly spherical. So, if, has been suggested, they were for a prehistoric game of marbles, they wouldn’t have rolled far.
The Ness assemblage has been examined and catalogued by David and Helen Smith, who noted that the majority were marked with either punch-marks or incised lines before firing.
They, like others , have suggested they were used as some kind of counters or game pieces, the flattened bottoms to stop them rolling.
An interesting possibility is that they were used in cooking.
It has been proposed that clay balls found at Çatalhöyük, Turkey, served as a type of grill.
These had a short lifetime and at Stonehall it was suggested that had they been used in the preparation of food, the used clay balls had not survived. 
With this in mind, it is noteworthy that analyis of the Stonehall examples showed that a few “had been exposed to moderate heat, that is, over 100 deg C.” 
Another suggestion from Stonehall proposed they may have been temporary “feet” to stand hot vessels on. 
While this would certainly account for the squashed appearance of those from the Ness, one cant help but wonder whether a stone slab would have been easier and just as effective.
-  MacSween, A. (2007) The pottery. In Hunter, J. with Bond, J. M. and Smith, A.N. (eds) Investigations in Sanday, Orkney: a multi-period settlement from Neolithic to Late Norse times. Kirkwall: The Orcadian Ltd.
-  Jones, A. M., Jones, R., Tully, G., Maritan, L., Mukherjee, A., Evershed, R., MacSween, R., Richards, C. and Towers, R. (2015) Prehistoric Pottery from Sites within the Bay of Firth: Stonehall, Crossiecrown, Wideford Hill, Brae of Smerquoy, Muckquoy, Ramberry and Knowes of Trotty. In Richards, C. and Jones, R. (eds) The Development of Neolithic House Societies in Orkney: Investigations in the Bay of Firth, Mainland, Orkney (1994–2014). Windgather Press.