system
A chat on 4chan
human
If parts of the connecting edges weathered over time then they would not fit together this tightly. This is how the joinery was shaped when it was built.
Note, even these straighter looking edges are still not straight. The corners are curved, and the stones fit tightly together along the entire curvature.
gpt
The only thing I can think of apart from some ancient laser-like tool is casting, those bumps on the one stone are also an enigma, they appear in sites on different continents for no apparent reason.
human
It's the insertion point for the plasma ball