Just a load of questions :) If they're made of granite aren't they awfully hard? Has anyone tried to make one in recent times? I'm imagining it would be a right pain in the behind. They are marvelously symmetrical, another thing that wouldn't be easy - so they are surely the work of someone who really knew what they were doing? Could they not just be 'Art' (that is, without a practical use) or someone showing off their superior stone-working techniques? and so such a fine and unusual object would have a high value (not necessarily a monetary value).

Sorry to be so ignorant, but what kind of locations have they been found in?