The Dodecahedron: Ancient Toy or Practical Tool?

In June of 2023, amateur archaeologists working at a dig site in Norton Disney, a small village in the English Midlands, found a strange artifact buried in a Roman-era grave site. Three inches tall and weighing half a pound, the copper alloy object had 12 flat pentagonal faces, each with a differently sized hole opening up to its hollowed-out center. Each of the shape’s 20 vertices was studded with a small spherical knob. Richard Parker, who was part of the team that discovered it, later told the BBC about the excitement on the scene: “Oh my goodness me, you’ve found a dodecahedron! I’ve only read about those, I’ve never seen one!”

The object was both mysterious and familiar: Nearly 130 similarly shaped artifacts have been discovered across the former Roman holdings in England and northern Europe since June 28, 1739, when a man called George North walked into a meeting of the London Society of Antiquaries and “shewed a piece of mixed metal, or ancient brass, consisting of 12 sides” that he had found in a field along with some old coins.

Since then, dozens of similar 12-sided objects have been unearthed in archaeological sites or found in collections of oddities in England and northern Europe from France to Hungary. Their sizes vary from 1 to 5 inches, but nearly all of them were made from similar materials (usually a copper alloy), using similar techniques (the high-skilled lost-wax metal casting process).

The objects, many of which were found in graves or buried treasure hoards, were clearly valuable and important to their owners, but the historical record has provided scant clues as to why they were made or how they were used. No references have been found in surviving writing or art from the era. Even their common name is simply a modern description of their culture of origin and physical form: the “Gallo-Roman dodecahedron.”

During the first through fourth centuries A.D., the era during which most of the dodecahedrons seem to have been manufactured, northern Europe was the site where Roman culture mixed with that of Gaul, the set of regions conquered by Julius Caesar in 50 B.C. The fact that the dodecahedrons have been discovered only on the fringes of the Roman Empire, without obvious antecedents in either Roman or pre-conquest Gallic culture, suggests that may have emerged in such an interchange.

Scholars have proposed dozens of possible explanations for the dodecahedrons’ uses. Their regular design and pattern of differently-sized holes suggest they might have been some sort of tool or toy—perhaps as a variable-width candleholder, a hand loom for knitting gloves, a calibration gauge, a rangefinder, a variant on the cup and ball game, or as a tool for measuring the angle of the sun to know what date to plant wheat.

Detractors of the tool theories note that few of the objects show the kind of wear and tear associated with practical use, and that real-world tests with replicas of dodecahedrons show they are not particularly effective at any of these tasks. Furthermore, the lack of nondecorative markings and standard sizing argues against their being useful for measuring things. And although their shape suggests a 12-sided die used in gambling or divination, the artifacts’ irregular weighting makes them useless for those purposes.

Other historians have suggested that a ritual or religious function is more likely. One dodecahedron unearthed in a grave in Germany during the 1980s had been buried next to a piece of deteriorated bone that may have at one time been attached to it. This suggested it may have served as the head of a wand or ceremonial mace.

The dodecahedron itself has long been known in Greco-Roman geometry and philosophy as of one of the Platonic solids along with the tetrahedron, cube, octahedron and icosahedron. In Plato’s dialogue Timaeus, the title character describes the solids and their symbolism: “And there is a fifth figure (which is made out of twelve pentagons), the dodecahedron,” he says. “This God used as a model for the twelvefold division of the Zodiac.” But the Gallo-Roman dodecahedrons are not solid but hollow, and lack any constellation markings that would prove an astrological purpose.

It’s also possible, though, that the answer to the mystery of the Gallo-Roman dodecahedrons' use is that they didn’t really have one, but were simply knickknacks—impractical objects valued and treasured for their form and for the skill it took to make them.