A Roman dodecahedron or Gallo-Roman dodecahedron is a small hollow object made of copper alloy which has been cast into a regular dodecahedral shape: twelve flat pentagonal faces, each face having a circular hole of varying diameter in the middle, the holes connecting to the hollow center. Roman dodecahedra date from the 2nd to 4th centuries AD and their purpose remains unknown. They rarely show signs of wear, and do not have any inscribed numbers or letters.
The first dodecahedron was found in 1739. Since then, at least 116 similar objects have been found in Austria, Belgium, France, Germany, Hungary, Luxembourg, the Netherlands, Switzerland and the United Kingdom. In 2023, a dodecahedron in excellent condition was found by amateur archeologists in the small village of Norton Disney in Lincolnshire, UK, bringing the total to 33 of such objects found on the territory of Roman Britain.
Instances range in size from 4 to 11 centimeters (1.6 to 4.3 in). A Roman icosahedron has also been discovered after having long been misclassified as a dodecahedron. This icosahedron was excavated near Arloff in Germany and is currently on display in the Rheinisches Landesmuseum in Bonn.
Convex regular icosahedron
Great icosahedron
No mention of dodecahedrons has been found in contemporary accounts or pictures of the time. Speculative uses include as a survey instrument for estimating distances to (or sizes of) distant objects, though this is questioned as there are no markings to indicate that they would be a mathematical instrument; as spool knitting devices for making gloves (though the earliest known reference to spool knitting is from 1535, and this would not explain the use of bronze or the apparently similar icosahedron which is missing the holes necessary for spool knitting); as part of a child's toy; or for decorative purposes.
I guess we can now add, candlestick holder, bell, & ammo to the speculative list, but I will go with decorative purposes, A.K.A knickknacks. 😋
The Roman dodecahedron still looks dangerous to me though. Could be a weapon of convenience, much like a candlestick holder or a brass bell of considerable weight. 🤣