Exa, the daughter of Grimes and Elon Musk, is given the symbol for curiosity as her new name.
The one-year-old goes by "Y now, or 'Why?' or just '?'," the singer tweeted on Thursday.
Grimes, whose real name is Claire Elise Boucher, acknowledged that the emblem, which stands for "curiosity, the everlasting inquiry,.. and such,"
The 35-year-old Canadian musician secretly gave birth to a girl through surrogate in December 2021 and kept the child under.
After Exa started crying during the interview, she told Vanity Fair, "I don't know what I was thinking" about trying to hide her "colicky" baby's presence.
At the time, Grimes reported that her child went by the moniker "Y."
The on-again, off-again couple also has a 2-year-old kid. They first "semi-separated" in September 2021.
His first name did not abide with the laws of California.
After their son was born in May 2020, Grimes and the Twitter CEO altered his name from X AE A-12 to X AE A-XII in order to comply with the law.
Grimes tweeted that AE was the "elven spelling of Ai (love &/or Artificial intelligence)" and that the first letter stood for "the unknown variable."
"A-12 = predecessor to SR-17," she continued (our favorite aircraft). Only speed, no defenses or weapons. Excellent in combat but non-violent. Archangel is one of my favorite songs.
The same month, Musk stated that the moniker was chosen by Grimes in a conversation with Joe Rogan.
First of all, he explained, "much of the credit for the name actually goes to my partner. It's just the letter X, after all. The AE is thus pronounced like "ash."
With his ex-wife Justine Musk, the Tesla co-founder is also the father of five children: the 19-year-old twins Griffin and Vivian, as well as the 17-year-old triplets Kai, Saxon, and Damian.
Musk received yet another set of twins in November 2021 along with Shivon Zilis, a Neuralink executive.