Elon Musk, the billionaire entrepreneur, and Grimes, the singer, have welcomed their second child, a girl called Exa Dark Sideræl Musk, though her parents will refer to her as Y.
In an interview with Vanity Fair published Thursday, the 33-year-old Grimes disclosed the birth of the child, who was born in December.
And it appears she did so by accident: during the interview at Grimes' home in Texas, the magazine reporter stated he heard what sounded like a baby wailing upstairs, and although Grimes grimaced and played evasively, she ultimately revealed that, sure, she was a mother again.
The parents opted to hire a surrogate this time because they were afraid she would have difficulties, as Grimes said she had during her first pregnancy.
The birth of their first child, a boy born in May 2020, was widely publicized, particularly because of the name they chose: X A-12, or simply X.
Elon Musk, the CEO of Tesla and SpaceX and the world's richest man, said last October that he and the singer were "semi-separated."
"I'd call him my boyfriend," Grimes told Vanity Fair, "but we're very fluid." Musk and the diverse artist, whose real name is Claire Boucher, reside in separate houses but are "close friends," according to Boucher.
Grimes revealed that she and Musk want to start a family: She stated, "We've always wanted at least three or four."
Exa refers to supercomputing; Siderl, a more "elven" form of sidereal - this word meaning involve faraway stars - and Dark, Grimes explained, are all references to space and technology.
"Dark matter is the beautiful mystery of our cosmos," Grimes said, adding that she hasn't ruled out the possibility that her daughter would change her name in the future.
At her house in Austin, Texas, she told Vanity Fair, "The optimum arrangement here is me training the girl and him training the boy."
Musk has revealed that his primary house is now in southern Texas, at SpaceX's rocket manufacturing and launch location, after recently selling all of his Los Angeles real estate.
During a virtual presentation on the space company's new rocket in November, the blond-headed X could be seen sitting in his father's lap.
Musk, 50, has been divorced three times and has eight children, one of whom died at the age of 10 weeks.
