Elon Musk and artist Grimes have a child together called “X” (short for X Æ A-12), and it has just been revealed that they actually also have another child together called “Y.” And, Grimes confirmed after that their daughter’s full name is Exa Dark Sideræl Musk.

They had Y via surrogate after a difficult pregnancy with X. They want to have at least three to four children, too.

Key comments:

“We are semi-separated but still love each other, see each other frequently, and are on great terms. It’s mostly that my work at SpaceX and Tesla requires me to be primarily in Texas or traveling overseas and her work is primarily in LA She’s staying with me now and Baby X is in the adjacent room,” said Musk in late September of last year.

When talking about her relationship recently, Grimes said, “There’s no real word for it. 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.”

Since the article was published, though, Grimes tweeted that she and Musk have split up once again.

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