Grimes Shares Rare Photo of Her and Elon Musk's 'Hardcore' Daughter Exa, 9 Months: 'What a Queen'

Dia Dipasupil/WireImage, Grimes/Twitter

Grimes and Elon Musk's daughter is growing up fast!

The singer, 34, recently shared a rare photo Twitter of daughter Exa Dark Sideræl, nicknamed Y, listening to music and playing with a copy of The Birth of Tragedy by German philosopher Friedrich Nietzsche.

"My daughter is dancing to techno over this copy of the birth of tragedy by Nietzsche - what a queen," she tweeted alongside the shot of the 9-month-old leaning on a bench in a black onesie with a pink bow headband in her blonde hair.

"She loves Boris Brejcha omg she's so hardcore haha," the mom of two, who also shares 2-year-old son X Æ A-12, with the Tesla founder, said in a follow-up tweet.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

RELATED: Elon Musk, Who Secretly Welcomed Twins Last Year, Congratulates Nick Cannon on His Growing Family

Along with Y and X, Musk shares twins with Neuralink executive Shivon Zilis, whom he welcomed last November.

In addition, he shares 18-year-old twins Vivian Jenna Wilson and Griffin Musk, along with triplets Kai, Damian, and Sax Musk, who were born in 2006, with his first wife, Justine Wilson. The two had another son, Nevada Musk, who died at 10 weeks.

Last month, Musk shared a throwback photo on Twitter of him and X from Thanksgiving last year.

"Thanksgiving last year after watching one too many episodes of Vikings," he captioned the photo, which showed him and the toddler in an outdoor setting.

Fans noticed Musk sporting a shaved head on the sides, with a Tesla fan account asking if he cut his own hair and X's himself. "Yeah," the tech mogul replied.

Theo Wargo/Getty Elon Musk with son X

Grimes first told Vanity Fair that she and Musk welcomed a daughter in December 2021 via surrogate in a cover story for the magazine's April 2022 issue.

The singer explained her daughter's unique name to the outlet, telling Vanity Fair that Exa refers to a supercomputing term, exaFLOPS, while Dark represents "the unknown." She explained, "People fear it but truly it's the absence of photons. Dark matter is the beautiful mystery of our universe."

At the time, she told the outlet that they plan to have more children too: "We've always wanted at least three or four."