Elon Musk and Grimes become parents again, names her Exa Dark Sideræl Musk

Billionaire Elon Musk and singer Grimes secretly welcomed a second baby, named Exa Dark Sideræl Musk, via surrogate in December. The baby girl, nicknamed Y, is Grimes' second child and Musk's eighth.

The 33-year-old Grimes revealed the existence of the child, in an interview published Thursday by Vanity Fair.

And she did so by accident, it seems: the magazine reporter said he heard what sounded like a baby crying upstairs during the interview at Grimes' home in Texas and after Grimes first winced and acted evasively, she finally confirmed that, yes, she was a mom again.

The name Exa Dark Sideræl, Grimes explained, includes multiple references to space and technology: she said Exa refers to supercomputing; Sideræl, a more "elven" spelling of sidereal -- this word means involving distant stars -- and Dark, for "the unknown."

Due to fears that she would have complications, which Grimes said she endured during her first pregnancy, the parents decided this time to use a surrogate.

The birth of their first child, a boy born in May 2020, was followed closely in the press -- notably because of the choice of name: X Æ A-12, or more simply, X.

Elon Musk -- the head of Tesla and SpaceX, and currently the richest person in the world -- announced last fall that he was "semi-separated" from the singer.

The eclectic artist, whose real name is Claire Boucher, added that she and Musk live in separate houses but remain "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 said.

Grimes said she and Musk plan to have more children: "We've always wanted at least three or four," she said.