bestofwikipedia:

A Roman dodecahedron is a small hollow object made of bronze or stone, with a dodecahedral shape: twelve flat pentagonal faces, each having a circular hole in the middle which connects to the hollowed-out center. Roman dodecahedra date from the 2nd or 3rd centuries AD. The function or use of the dodecahedra remains a mystery; no mention of them has been found in contemporary accounts or pictures of the time. (via werttrew)