This is a miniature representation of the Aeolipile, described and probably invented by Hero of Alexandria in the 1st century AD (Wikipedia page). There are no contemporary pictures of the original, just a vague description; but it is usually shown as something like the bottom image on the left.
It is a reaction turbine, with no blades but three steam jets exhausting into the atmosphere. The roughly spherical boiler, 40mm diameter spins with the jets and is heated by a meths burner. It is supported by a needle bearing at the bottom and a miniature ball bearing at the top.