Imagine a square sinkhole.
The corners would be quite strong, they’re supported on either side, but the middles of the edges would be very liable to collapse inwards.
If you imagine pretty much any non circular shape, it will have weaknesses that will cause it to crumble *towards* a circle.
The circle is the “natural” shape because every point around the side is equally strong, so it will continue to hold its shape.
Latest Answers