Grimes and Elon Musk have a secret third child together and excuse me, what?

It's not all too often we get a glimpse into the world of billionaires, but this week we learnt a surprising little tidbit about Tesla founder Elon Musk – and it's that he doesn't just have two children with singer Grimes... but three. 

In a new biography documenting Musk's life, the author cheekily let drop that the pair welcomed a third baby in secret and, wow.

According to The New York Times, the couple has a son named Techno Mechanicus (which tracks given their other kids' names – we'll get to that). Little Techno also goes by "Tau".

Journalist Walter Isaacson wrote the book, which is set for release on September 12, and for now, the details about Musk's 11th child are scarce (though we're hoping that changes once the new tome hits bookshelves).

The couple, who Grimes confirmed had split (not for the first time) in March 2022, welcomed son X Æ A-12 – whose name was later changed to X Æ A-Xii and is nicknamed “X" – on May 4, 2020. And no, we have no idea how you're meant to pronounce that either. 

They then welcomed a daughter born via surrogate in December 2021, named Exa Dark Sideræl and nicknamed "Y." Aww! Love the classics. 

Aside from their difficult-to-say names, there's actually not all that much information around about Musk's three children with singer Grimes, except for the ever-so-rarely shared morsels Grimes occasionally likes to drop.

In a post to Twitter last year, Grimes showed a rare photo of baby Y wearing a black onesie and a pink headband, touching a copy of the Nietzsche book The Birth of Tragedy. Grimes accompanied the photo with the caption, "My daughter is dancing to techno over this copy of the birth of tragedy by nietzsche – what a queen."

My daughter is dancing to techno over this copy of the birth of tragedy by nietzsche - what a queen pic.twitter.com/GajRCEVDen

— 𝔊𝔯𝔦𝔪𝔢𝔰 (@Grimezsz) September 18, 2022

She later added in a reference to her daughter's musical tastes, writing: "She loves Boris Brejcha. She’s so hardcore."

But they kept that one under wraps for a while, too. In fact, it wasn't until Vanity Fair journalist Devin Gordon visited her home in March 2022 for an interview and heard a 'mystery' baby crying upstairs that Grimes announced Y's arrival. 

She explained that privacy and the pandemic were both factors in the secrecy around her birth.

"Whatever is going on with family stuff, I just feel like kids need to stay out of it, and X is just out there," Grimes told Gordon of her son with Musk.

"I think E [Musk] is really seeing him as a protégé and bringing him to everything and stuff... X is out there. His situation is like that. But, yeah, I don’t know."

She told Gordon that she was very unwell during her first pregnancy, even fearing she might die, which led to the couple's decision to use a surrogate for their second child together.

"He was pressing on my nerves, so I kept collapsing," she said of her pregnancy with X. 

"I took a few steps and collapsed. It was kind of scary, because you don't want to fall a lot when you're eight months pregnant."

While Grimes tweeted that she and Musk had broken up again after the Vanity Fair interview was published, she confused fans by saying that Musk is her "best friend and the love of my life."  

Their fluid relationship appears difficult to define. 

"There’s no real word for it," she told Gordon. 

"I would probably refer to him as my boyfriend, but we’re very fluid. We live in separate houses. We’re best friends. We see each other all the time. We just have our own thing going on, and I don’t expect other people to understand it," she continued. 

"This is the best it’s ever been. We just need to be free."

In September 2021, Elon Musk confirmed that he and Grimes had separated, but continue to co-parent their children together.

"We are semi-separated but still love each other, see each other frequently, and are on great terms," he said.

"It's mostly that my work at SpaceX and Tesla requires me to be primarily in Texas or travelling overseas and her work is primarily in LA.

"She's staying with me now and Baby X is in the adjacent room."

The 51-year-old Tesla founder and billionaire allegedly welcomed twins in late 2021 with Neuralink executive Shivon Zelis.

He is already dad to twins Griffin and Xavier, and triplets Damian, Saxon and Kai, from his previous marriage to author Justine Wilson. Sadly, his son Nevada Alexander died of sudden infant death syndrome (SIDS) at 10 weeks old in 2002.

While it seems Musk is comfortable in his role as a father, Grimes has described her inability to relate to the word 'mother' in a video for Vogue.

"I think having a baby was a big rebirth for me, like, artistically," she said in the video.

"Being a mother feels weird to say. For some reason I don't identify with that word. Which is also really weird because X, he says 'Claire,' but he doesn't say 'Mama'... maybe he can sense my distaste for the word mother," she continued.

"I don't even know why I have a distaste for [the word] because I respect... I just, I don't, I can't identify with it, weirdly."

View this post on Instagram

A post shared by ☘︎𝔊𝔯𝔦𝔪𝔢𝔰࿎ (@grimes)

Her children's unusual names have garnered much attention and Grimes has had to explain her choices. 

When X was first born, Grimes tweeted: "X, the unknown variable. Æ, my elven spelling of Ai (love &/or Artificial intelligence) A-12 = precursor to SR-17 (our favorite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent + (A=Archangel, my favorite song) (metal rat)."

The couple had to change part of his name shortly after his birth because of Californian law not allowing numerals or symbols as part of a baby's name.

Grimes shared in an Instagram comment that the couple made one small change to their son's name, explaining that "X Æ A-12" is now spelled "X Æ A-Xii." She later added: "Roman numerals. Looks better tbh."

Grimes rose to fame with the release of her third studio album Visions in 2012 and her sixth highly anticipated album, BOOK 1, is coming soon.

This article was published on September 27 2022 and has since been updated with new information.

Feature Image: Getty.

Do you buy groceries for your household? Take our survey now to go in the running to win a $50 gift voucher!