"Earth-scale gravity is so strong that a cube made of the strongest rock would soon be deformed into a ball." Not necessarily true. If the cube-shaped world ha

"Earth-scale gravity is so strong that a cube made of the strongest rock would soon be deformed into a ball." Not necessarily true. If the cube-shaped world has a cube-shaped moon orbiting at the same period as our moon, it will be sooner transformed into a ball by creepers.