Elon Musk has turned a long-running joke about being an extraterrestrial into a central part of his public persona, even as he argues that humanity may be the only intelligent life in the universe.

Elon Musk claims he's an alien—and frustrated nobody believes him. Discover the billionaire's escalating extraterrestrial ...

Quite a bit of movie magic made "Alien" the sci-fi horror classic it is -- but one of its biggest challenges was solved with a simple low-tech tactic.