Elon confirmed the birth of their baby on Twitter, simply writing, "Mom [and] baby all good," in response to his tweet a few hours earlier that read, "A few hours away!"
Elon responded to a fan asking about the baby's name, to which the billionaire responded, "X Æ A-12 Musk."
Twitter users quickly began questioning how the name is pronounced, but received no answers.
Others questioned if he was being serious.
He also confirmed the baby was a boy, making him Elon's sixth son. However, Grimes has previously said in a YouTube live stream, which has since been made private, that she wants to allow the baby to choose its own gender.
"I don't want to gender them in case that's not how they feel in their life... I don't know, I just feel like it doesn't need to be known... They may decide their fate and identity."
The pair have been dating for two years, making their debut at the Met Gala in 2018 (the 2020 Met Gala would have been held today).
Grimes announced she was pregnant on Instagram in January, but didn't confirm that Elon was the child's father until an interview with Rolling Stone in March.
In an interview with The Face in February, Grimes revealed how she was preparing for her baby, which included creating a digital version of herself, named WarNymph so she can continue to do shows, photo shoots and more without having to be physically present.
"Having a digital body allows me to keep working throughout the later stages of my pregnancy, and after I have my baby, so I can spend more time with them. It's hard for me to do photoshoots and fit into clothes at the moment, but WarNymph is here in your magazine promoting my album for me," she told the mag.
She described the solution as "techno-feminism", saying, "A lot of my friends aren't having babies because they're worried about their careers, and we wanted to find a way to overcome this issue."
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