Elon Musk's bizarre message about aliens building the pyramids of Giza has prompted a response from the Egyptian goverment - and Helen Clark.
After the billionaire shared on Twitter an old conspiracy theory that the pyramids were built by extraterrestrials, a top Egyptian official invited the SpaceX and Tesla founder to come and see one of the "seven wonders of the ancient world" for himself.
On Friday Musk tweeted: "Aliens built the pyramids obv."
He followed up the message by saying: "The Great Pyramid was the tallest structure made by humans for 3800 years."