Elon Musk says his newborn son is named X Æ A-12

The tech billionaire Elon Musk and the musician Grimes have welcomed their first child together. both Grimes and the baby were doing well.

But the Tesla and SpaceX CEO has already caused confusion over the baby’s name, which he tweeted was “X Æ A-12 Musk.”

While it’s not clear whether Musk was joking, many of his and Grimes’ fans have interpreted the name as something of a riddle, floating their best guesses for what the string of characters means.

One Twitter user interpreted the name as “X Ash Archangel” – “Æ” is pronounced “ash,” and “Archangel” was the internal codename for the CIA’s A-12 aircraft. Musk liked the tweet, leading people to believe it was the right guess.