evidence: "The world is flat and I can’t get past the firmament!" read what looked like an April 25 tweet from Musk, referring to an unfounded belief that Earth is covered in a dome called the firmament. The tweet then followed up with a question that lacked a question mark: "Anyone want to buy SpaceX," it read. [...] Musk has poked fun at the idea that Earth is flat, tweeting in November 2017: "Why is there no Flat Mars Society!?" [...] We rate claims that Musk tweeted the world is flat False.