Torus/Donut Planets

The Halo ring might be a little different. The thin, regular structure always implied to me that it was meant to be artificial, perhaps even a slimmed version of a Dyson sphere. That it has a reasonably flat cross-section (unlike a donut) might be the strongest evidence that it's artifical, but that's just a hypothesis of mine.

I'm was pretty surprised that the math allows for any shape other than shere (or sphere-ish). This could complicate the definition of planet a bit more too, since a defining feature of a planet is having enough mass to round out it's surface. If we could ever take direct photographs of distant systems it would be a pretty neat discovery to find one "in the wild".

Since one good whack from a space-rock could basically explode the planet I wonder how a fantasy civilization might protect against that. Assuming they advance far enough to predict/detect such threats (divination?) how would they defend against them? Some sort of planetary shield? A mystical version of a gravity tractor? Some sort of stupidly powerful teleportation spell to move the rock somewhere else?

Would such a society grow all of their food on the exterior, leaving the interior an eternally dark, frozen wasteland with wonky gravity? How would tides even work? Volcanoes? Air currents? It's an interesting scenario to try and wrap my imagination around.