Grimes and Elon Musk welcomed a second child, a girl named Exa Dark Sideræl Musk, via surrogate in December, the singer revealed in a wide-ranging interview with Vanity Fair published on Thursday. The Canadian singer, born Claire Boucher, was initially reluctant to reveal the couple’s second child, nicknamed “Y”, but during an interview at her home in Austin, Texas, Vanity Fair journalist Devin Gordon overheard a baby crying. When asked if she had a new baby in her life, the futurist pop singer initially said she wasn’t “at liberty to speak on these things” but then confirmed Y joined the family in December, and eventually shared her full name. The on-again, off-again couple – “I would probably refer to him as my boyfriend, but we’re very fluid,” she told Vanity Fair – welcomed their first child, X Æ A-12 (pronounced “X AI Archangel” and nicknamed “X”), in May 2020. Y is the second child for Grimes and Musk’s eighth. His first child, son Nevada Alexander with ex-wife Justine Wilson, died at 10 weeks of sudden infant death syndrome (Sids) in 2002. Grimes told Vanity Fair that the name Exa refers to the supercomputing term exaFLOPS, or the ability to perform 1 quintillion floating-point operations a second. Dark, she said, represents “the unknown. People fear it but truly it’s the absence of photons. Dark matter is the beautiful mystery of our universe.” Sideræl is pronounced “sigh-deer-ee-el” and is a “more elven” spelling of sidereal, “the true time of the universe, star time, deep space time, not our relative earth time”. The name also honors her favorite Lord of the Rings character Galadriel, who “chooses to abdicate the ring”. Grimes expressed throughout the interview a desire to keep her daughter’s likeness and details private; following its publication, she tweeted: “I did this to speak abt my work, not ‘reveal all’ haha. Def held back a lot, contrary 2 headline. & didn’t mean for them 2 find out about my daughter so please respect her privacy as I’d love her to be able to live as private of a life as possible.” She also added in a separate tweet that she and Musk, a billionaire who also founded SpaceX and NeuraLink, among other tech companies, had “broken up *again* since the writing of this article haha, but he’s my best friend and the love of my life, and my life and art are forever dedicated to The Mission now, I think Devin wrote that part of the story rly well”.