The case in 60 seconds
Roman dodecahedra are among this series' clearest examples of a genuine mystery: their existence, date and manufacturing technique are known, but their purpose is not.
Approximately 130 examples are currently known. Most come from Gaul, Britain, Germania and neighbouring northwestern Roman provinces. The absence of examples in Italy is notable.
They are hollow copper-alloy polyhedra. Each of their twelve pentagonal faces has a circular hole of a different diameter, and each of the 20 corners has a small knob. Their dimensions are not standardised, however, and no known ancient passage describes them.
Proposed functions include measuring instruments, candleholders, knitting tools, military rangefinders, moulds, gaming objects, astrological instruments and divination/ritual objects. None has yet settled the debate.
The claim
“The Romans made hundreds of these complex bronze objects but never wrote down what they were. Perhaps they were secret military instruments, advanced calculators or products of lost technology.”
The first point is true: we do not know their function today. But that does not establish “secret advanced technology”. What is surprising is that no textual or iconographic explanation of an object represented by hundreds of examples has survived.
What we know
The evidence
1 — The difficulty for the measuring-instrument theory: they are not standardised
If dodecahedra were regular military or engineering measuring tools, some standards in hole diameters, opposing faces or overall dimensions would be reasonable to expect. Yet specimens vary significantly in size and weight.
The Norton Disney team also questions the “measuring device” theory, emphasising the new find's lack of standardised measurements.
Weakens the measuring theory2 — Heavy use-wear is generally absent
The specimen found in the 2023 Norton Disney excavation in Lincolnshire is complete and in excellent condition. The research team reports no obvious wear suggesting regular mechanical use. This is an important clue against theories of an everyday production tool.
Against practical-tool theories3 — Why does the 2023 Norton Disney find matter so much?
Where many older dodecahedra lack a precise excavation context, the Norton Disney example was found in a controlled archaeological excavation, in a large pit about one metre deep. Its copper-alloy analysis gave approximately 75% copper, 7% tin and 18% lead. Fourth-century Roman pottery nearby strengthens a late Roman context.
A rare, well-documented context4 — Even Norton Disney has not solved the mystery
Further excavations in 2024 and 2025 did not establish why the object was deposited in that pit. The Royal Archaeological Institute report explicitly states that there was no obvious evidence of ritual deposition. Even one of the best-contextualised examples therefore does not reveal its function.
The mystery continues5 — Why is the ritual/astrological theory taken seriously?
The Grand Curtius Museum in Liège notes that dodecahedra may be connected with Celtic traditions in the northwestern Roman provinces, and that the astrology/divination theory is particularly interesting. A dodecahedral die-like object found in Geneva, bearing zodiac names on its faces, provides a comparative clue that the dodecahedral shape could be used in divination.
But this does not directly establish that it served the same function as the perforated bronze dodecahedra.
Interesting contextual support6 — Working as a “knitting tool” is not enough
Modern replicas have been shown to make glove fingers or tubular knitting. Yet an object performing a task today does not establish that it was made for that purpose in antiquity. Bronze is also expensive and heavy; simpler wooden devices could perform the same task.
Function ≠ historical evidenceTheories
Theory A — A ritual / divinatory / astrological object
Strength: Lack of standardisation, limited wear, considerable production effort and some sacred/funerary contexts may fit symbolic value better than a utilitarian tool. Concentration in the northwestern provinces strengthens the possibility of a local religious tradition.
Weakness: No Roman depiction shows a dodecahedron in a ritual, and no text names it. “Ritual” can sometimes be an easy fallback explanation for objects of unknown function.
Theory B — A distance / size measuring or optical sighting instrument
Strength: Looking through opposing holes of different diameters changes the field of view; angles or distances could theoretically be estimated.
Weakness: Specimens are not standardised, most lack measurement markings, and no known Roman text describes this method.
Theory C — A knitting / glove-making tool
Strength: Replicas can be used to knit yarn in practice.
Weakness: There are no direct traces of ancient knitting use; bronze is unnecessarily expensive, and clear ancient parallels for the relevant “spool knitting” technique are weak.
Theory D — A candleholder
Strength: Claims of beeswax residues inside some specimens gave rise to this theory.
Weakness: The design is excessively complex and expensive for a candleholder; wax could have arrived through other uses. Shared evidence is absent across all examples.
Theory E — A masterwork / status object
Strength: Manufacture by lost-wax casting requires considerable metalworking skill; they may have demonstrated craftsmanship or served as prestige objects.
Weakness: This does not, by itself, explain why the same distinctive hole-and-knob design recurs across a broad geographical area.
Theory F — Multiple functions
Strength: Different sizes and contexts leave room for regional or chronological variation rather than a single use.
Weakness: Continued preservation of the same basic design may suggest a shared core meaning or function.
What remains unknown
My assessment
🔴 This time, we really do not know the answer to “What was it for?”
Like Voynich, Roman dodecahedra present a genuinely open problem, but for a different reason. It is not that we cannot read the text; the object itself is silent.
On my reading of the evidence, the most plausible broad category is ritual / symbolic / divinatory. I regard this not as a “solution”, but as the working hypothesis that best fits the available data: lack of standard dimensions, limited wear on some specimens, expensive bronze production and a distribution specific to the northwestern provinces support it.
The crucial point, however, is: we cannot yet assign 🟢 to any theory. As well-contextualised new finds like Norton Disney accumulate, the mystery may eventually be solved.
The object's period, geography and manufacture are known; its basic purpose is not.
References
Museums, universities, archaeological institutions and recent excavation reports were prioritised as sources.
Grand Curtius
Newcastle University
Norton Disney Dodecahedron
RAI Newsletter
Roman Society
Last updated: 6 October 2026.