A black hole.
Any rotating/spinning black hole will no longer be a perfect sphere.
But even then, the biggest black hole we think is possible measured down to the planck length gives you a number with 50 digits. And the entire observable universe measured in planck lengths is about 60 digits.
So how are you going to get a physical pi of even a hundred digits on the path toward arbitrary precision?
> > The idea of arbitrary precision is intrinsically broken in physical reality.
There is no contradiction here.