Its purpose is well documented!

https://scp-wiki.wikidot.com/scp-184

Easy. Twelve men gather ‘round and insert their penises (or penii back then) and try to make them meet in the middle. Whomever has the shortest penis that does not gingerly meet the others, draws the equivalent of the short straw, and performs whatever unfavorable task the men fetched the ol’ dodecahedron in order to determine in the first place. This game was of course unfair, as the man with the largest penis was always the first to suggest the dodecahedron, and the men with the smallest penii were practically serfs among their respective groups of friends.

I like how everything has to have some purpose.

It’s entirely possible that this was a useless decoration or something.