The term “squaring the circle” originates from ancient developers of geometry and refers to the challenge of constructing a square with the same area as a given circle. It was proven to be impossible in 1882, when pi was proven to be a transcendental, and not an algebraic irrational number.
It is now used sometimes as a metaphor for trying to achieve the impossible.
On a much more down to earth note, I was practicing throwing bowls on the wheel yesterday and when I finished one I thought it would be interesting to hake a square topped bowl just for the sake of it. So, this is the first stage of my impossibowl, as I wait for it to dry a little before further manipulation…