My theory is that #Roman_Dodecahedrons are combination stands and hand-holders for the #Roman equivalent of Rushlights.

The multifaceted design means you can always find the hole at the top for your unlit rushlight even in pitch black; and it is easy to manipulate the stalk of the rushlight into a corner at the base.

The bobbles stop it slipping out of your hands, and potentially keep your hand away from the face nearest the expose flame.

https://en.wikipedia.org/wiki/Roman_dodecahedron

#Dodecahedron

Roman dodecahedron - Wikipedia

The multifaceted design also means you can have multiple rushlight stalks sticking out from different faces simultaneously if you want more light and wider coverage, with the different size of the apertures giving you trade-offs between how securely a stalk is kept; how easy it is to get a stalk in; how easy it is to get spent stalks and ash out again; how many stalks you can potentially bundle and of what thickness; etc.