I know it’s fun to jump to aliens…
…but c’mon, people. Occam’s Razor time. There are a lot of options to exhaust before to we get to extraterrestrial intelligence. Just because we can’t explain this doesn’t mean its aliens. It’s a hell of a leap, bordering on religious faith, to credit this to some alien species crossing the vast lightyears of space and time to bounce around some metal spheres.