Interesting though that an apparently completely unrelated design retains the vertice knobs.
Does anyone know what any of these non-Roman ones were for?
I’m not sure I would say it’s completely unrelated, unless you’re referring to construction. There are still large holes, but they’re sorta hexagon shaped, and not circles. And yea, those knobs seem important.
There are lots of theories for the Scottish petrospheres - weights, bearings, grinders, etc., but they don’t show much sign of wear.
The silver-plated lead twelve-sided die with astrological labels would most likely seem be for fortune telling.
Iron dodecahedrons maybe don’t exist.
The gold ones are tiny and seem to be strung together with beads as bits of jewelry.
Okay, I’ve read through this entire thread, and I have some thoughts.
There’s been a good bit of debate about why, if the Romans are making these objects, why are they only found in the Celtic part of the empire? The obvious answer would seem to be that the Romans aren’t making them – the Celts are. This explains why we have no Roman descriptions or depictions of them.
Someone upthread (I’m sorry, I can’t find the post now) asked what kind of object can be used in the same way, no matter what size it is. And I think the answer had already been suggested by a poster who had asked if anyone had tried supping one on a string and hitting it with a stick. Bells all work the same no matter what size they are.
If they are bells, it provides a plausible explanation for the different sized holes: the sizes of the holes aren’t important – they’re simply a convenient means of removing differing amounts of metal, to tune each bell to a particular pitch.
Perhaps all those knobs were used to string a set of bells to a framework, like tubular bells, so you could play a tune.
Oh, and if they are bells, that neatly explains why we don’t find them made in any other material – that just wouldn’t work.
By the time these were being made, there was a distinct Gallo-Roman culture, which is generally considered to be the people who made these (hence the alternate name “Gallo-Roman Dodecahedrons”
. BTW, “Celts” is considered a bit passé as a name for the wider set of cultures, nowadays.
Thanks for the correction. My point is simply that the absence of dodecahedra elsewhere in the Empire suggests that it’s the Gauls, and presumably Britons, in particular, who are producing them.
A code/cypher device?
Gallo-Romans, but yes, that’s the general thought. Which is why one explanation would be that they’re local cultic artifacts.
My question about your bell theory would be - why that particular shape? You only need one hole to resize for tuning. And if they were strung together in sets, why do we mostly find them singly?
I would say “You’re guess is as good as mine,” but yours would obviously be better 
At this point it seems that if we could go back in time and ask, it could be anything from “deeply significant cultural meaning” to “Oh, that was Steve’s idea. I thought he was daft, but we do seem to sell a lot of them”. It might even be “Of course they’re dodecahedrons – what shape are your bells?
I’m not wedded to stringing them in sets, I was just trying to think of a use for all those bloody knobs. Obviously they could simply be decorative, or have some other use.
One thing I do like about the idea is that it is testable. I appreciate that museum curators typically aren’t keen on hitting ancient artefacts with sticks, but maybe in the interests of science someone might give it a gentle go?
A dodecahedron would not be a simple bell. The sizes of the holes affect the harmonics. Which node is held fixed when rung will determine which harmonics would dominate.
Now why someone would want a bell that could be rung twenty different ways, I have no idea. Some sort of “magic eightball”?
To which the answer would be anything from round to pear-shaped to, you know, bell-shaped. Open-work bells are also not unknown from Romano-British contexts but they’re nothing like the dodecahedra.
Although it’s often the holder not the bells that could be an “interesting” shape:
You know, when you were posting earlier about Roman skill in casting bronze, that’s not at all the sort of image that came to mind
IMO anyone thinking the gizmos are suspended by the knobs on the vertices isn’t thinking too clearly about that aspect. Whether they think the gizmos are bells, a flavor of prayer wheel, or a sizing guage, or whatever.
Given the crude nature of twine in those days, and the large cross section of leather cordage, suspending one of these with a cord knotted around the base of a knob would be pretty insecure. Far better if the knobs were replaced by cast loops the cord could pass through. That would give reliable suspension.
Bottom line:
IMO the knobs are not points of attachment.
I feel confident WAG predicting(?) they are not bells, a term I mean to include all types of percussive noisemakers.
I’d sooner believe they’re (WAAAGing here) the heart of a wind instrument with textile & leather bellows and valves, reeds, wood, etc, all long gone. A wierd bagpipe dealie.
Why is this a given? Why do you think the Romans would have crude twine? Look at the cordage in this net. Nothing crude about it.
And they had thread of various types and horsehair. A heavier string could be made or braided from those materials. I don’t think the knobs were made for hanging, but not because of the lack of cord to use.
The material is no mystery, as that’s just selection bias. Any made from wood, leather, or other organic material would have rotted away, and iron or precious metals would eventually have been melted down to make something else. Bronze is both durable enough and cheap enough for at least some of them to have made it through the centuries to us.
It’d been proposed, but how? Most of the suggestions suffer from the flaw that they don’t actually use the dodecahedra themselves.
If iron was all going to be recycled, what makes you think bronze (way more valuable than iron) wouldn’t be?