Turns out Grimes and Elon Musk had another baby last year
Her name is truly something to behold.
Singer-songwriter Grimes has revealed that she and Elon Musk welcomed another baby last year.
The couple, who share baby X Æ A-Xii, had a daughter through a surrogate last December.
In an interview with Vanity Fair, the Oblivion singer shared her daughter's name which is Exa Dark Sideræl Musk, but that they call her Y for short.
Like big brother X, the little girl's name is rich in meaning. Exa is a nod to the supercomputing term exaFLOPs, and Dark, Grimes notes refers to the "absence of photons".
She added that while people may "fear" the name Dark, she finds it beautiful.
"Dark matter is the beautiful mystery of our lives," she said.
Her third name, Sideræl, is pronounced like "sigh-deer-ee-el", which Grimes says is an Elven form of the word sidereal, or "the true time of the universe, star time, deep space time, not our relative earth time".
In true Grimes fashion, Sideræl is also, apparently, a Lord of the Rings reference.
Grimes also gave an update on her "fluid" relationship with the tech billionaire.
She 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."
Grimes also shared that she plans on having more children with the Tesla boss.
After describing their relationship as "the best it's ever been", Grimes said: "We've always wanted at least three or four (children)."
Grimes also addressed the fact that they decided to keep the birth of baby Exa private.
She said: "I don't know. I don't know what I was thinking."