The Gallo-Roman Dodecahedron

Two ancient Roman bronze dodecahedrons and an icosahedron (3rd c. AD) in the Rheinisches Landesmuseum in Bonn, Germany.
Two ancient Roman bronze dodecahedrons and an icosahedron (3rd c. AD) in the Rheinisches Landesmuseum in Bonn, Germany.

The Roman Dodecahedron or Gallo-Roman Dodecahedron has long been an object of great mystery. It is a small, hollow object made of bronze or (less commonly) stone. Geometrically, it has 12 flat faces, with each face being pentagonal, decorated with a number of knobs at each of the corners of the pentagon, and having a circular hole of varying diameters connecting to the hollow centre.

Dodecahedron, 1st–4th century, bronze, Hunt Museum, Limerick, Ireland
Dodecahedron, 1st–4th century, bronze, Hunt Museum, Limerick, Ireland

The objects are quite small between 4-11cm (1.5-8.3 inches), and date from the 2nd to 4th centuries AD.

No references to these objects were found in the Roman texts, and even the excavated soil surrounding the objects refused to give away the truth. Either way, the object remains a great archaeological mystery, and a definitive answer will probably never come.

Discovery

The first object was found in 1739, and since then, more than 100 similar objects have been found in several places throughout the Roman Empire, such as Great Britain, Netherlands, Germany, Luxembourg, Austria, Switzerland, France, Belgium, and Hungary — mainly central and Western Europe.

An icosahedron has also been found that was originally misclassified as a dodecahedron, raising questions such as if there are other platonic solid-like objects still waiting to be found.

Roman Icosahedron
Roman Icosahedron
Platonic Solids - All five regular polyhedra, with information about faces, vertices and edges.
Platonic Solids – All five regular polyhedra, with faces, vertices and edges.

Similar objects appear not to have been produced before Gallo-Roman artefacts and could have been evidence of Roman influence in Funan, an ancient Indochinese kingdom.

Uses and Speculation

The function or usage of dodecahedra remains a mystery. There have not been found contemporary accounts in writing or paintings, or even in the excavated soil around the objects from the period to give us any reference as to what the objects were used for.

There are claims saying that the Roman Dodecahedra were used for decorative purposes only.

Some sources speculate that Roman dodecahedra were central objects of a bocce ball game, resembling the modern-day one, in which the artefacts were used as markers, with players throwing stones in order to drop them into holes inside the dodecahedra.

Roman dodecahedron, Schwarzenacker Roman Museum
Roman dodecahedron, Schwarzenacker Roman Museum

There are even theories that stipulate that the smallest Gallo-Roman Dodecahedra were used as candle holders since wax had been found on many of them, as well as handles made from gold.

Several dodecahedra were found inside hoards of coins, providing evidence their owners considered them to be valuable objects.

One of the more accepted theories is that Roman Dodecahedra were used as measuring devices or range-gauging objects in battle. Use as any sort of measuring instrument seems unlikely, since Roman dodecahedra were not standardised, coming in a variety of sizes and arrangements for the holes they had.

Other studies posit that the Gallo-Roman Dodecahedron was used as a sort of astronomic calendar in the Northern regions of the Roman Empire to mark the passing of the seasons and/or festivities; since they have not been found in the area across the Mediterranean territories: Spain, Italy, and Greece.

Map of Dodecahedron sites
Map of Dodecahedron sites

Some other hypothesized uses for this object are weights for fishing nets, musical instruments, toys for children, connectors for wooden or metal poles, and even gauges to calibrate water pipes. But so far all of these hypotheses remain unproven.

The knitting community has provided an interesting insight into another possible use for the Gallo-Roman Dodecahedron, and that is that it was used for knitting gloves.

Roman Dodecahedron Knitting Gloves
Roman Dodecahedron Knitting Gloves

Scholars, however, reject the theory that these objects were used for knitting because, given their size, they essentially could only make gloves for small children.

One of the most interesting theories floating around is that they could be dice for predicting the future in divination rituals. The idea for this comes from a particular dodecahedron found in Geneva in 1982 which had engraved faces with the names of the zodiac signs. In Plutarch’s The Moralia, the Greek historian reportedly identifies the dodecahedron as a vital instrument for zodiac signs, with the twelve sides representing the twelve animals in the Zodiac calendar.

However, most scholars do not subscribe to the idea of the Gallo-Roman Dodecahedra being instruments of oracle and divination. However, a number of icosahedron dice from the Hellenistic and Roman periods, usually from Ancient Egypt, have survived, all with Greek and or Latin engravings on each of their faces. A crystal icosahedron with Latin letters is also housed in the French Museum Louvre.

Crystal Icosahedron Die - Louvre Museum
Crystal Icosahedron Die – Louvre Museum

Or perhaps they were the original inventors of Dungeons and Dragons and other Role-playing games.

Perhaps the reason we have not found records of what they were used for, is that it was so obvious and simple to everyone that they did not see the need to explain its function.

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