Grimes has left her fans baffled after she recently posted a tweet supposedly clarifying her daughter's name.
The eccentric musician welcomed her second child with South African billionaire Elon Musk back in December 2021 via a surrogate.
Shortly after, the 35-year-old revealed the name of her daughter - who turned a year old just a few months ago - during an intimate interview with Vanity Fair.
The pair nicknamed the child "Y" before revealing that her full name was Exa Dark Sideræl Musk.
"It’s fire," she wrote via text to the journalist at the magazine, also adding: "Her full name is Exa Dark Sideræl Musk."
According to the outlet, "Exa" refers to the supercomputing term exaFLOPS, while "Dark" refers to "the unknown."
"People fear it but truly it’s the absence of photons. Dark matter is the beautiful mystery of our universe," Grimes explained.
Sideræl, which Grimes pronounced "sigh-deer-ee-el," is a "more elven" spelling of sidereal, the "true time of the universe, star time, deep space time, not our relative earth time," she added.
The name choice is also a reference to Grimes' favorite Lord of the Rings character, Galadriel - it's all pretty unique.
Elsewhere in the interview, she also admitted that she is concerned the baby’s name might actually be "boring", also recalling that her dream was to keep the name Odysseus Musk, though that was not possible.
"A girl named Odysseus is my dream," she added.
However, a recent tweet posted to social media suggests that the 35-year-old and Musk, who she refers to as her "boyfriend", might be looking to change their daughter's nickname to her actual government name.
Replying to a comment, Grimes clarified: "She's Y now, or 'Why?' or just '?' (But the government won't recognize that). Curiosity, the eternal question... And such."
Naturally fans were confused about the revelation.
One asked: "Her name is no longer Exa Sideræl?"
Another perplexed commenter penned: "But they allow the other names you choose??"
Not everyone disliked the suggestion though.
A third fan said: "Y is a nice name. I like the single letter."
"Awe, bless..she is such a sweet little cutie," added this user.
And this Twitter user described it as "cute," writing: "Baby Y soooo cuteee."
Grimes and Musk also share a son with a similar unique name, referring to him as Baby X, though his full name is a little more complicated - X Æ A-12.
Speaking of the inspiration behind the choice at the time, Grimes tweeted that there were several things they considered before finalizing the moniker.
The 'Shinigami Eyes' singer explained that the name includes references to her and Musk’s favorite "non-violent" aircraft, SR-17, and the elven spelling of AI, while the X is a reference to the "unknown variable" commonly used in math.
When questioned about the name, Grimes added: "I think it sounds like the name of the main character in the story. I hope he vibes with that. Ok, going back into the pain/ beauty reverie for sum time, just came on to add my thoughts. Peace to all."
So we have Baby X and Baby Y... Now all the couple needs is a Baby Z and they'll have the full shebang.
