When it comes to naming their kids, some stars are totally creative.
Right away, fans of Musk tried to decipher the meaning behind the moniker, with Grimes sharing additional details around the significance of his name.
"X, the unknown variable," she wrote on Twitter. "Æ, my elven spelling of Ai (love &/or Artificial intelligence) A-12 = precursor to SR-17 (our favorite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent. (A=Archangel, my favorite song)."
Musk and Grimes aren't the only celebrities to have standout names for their kid, either.
Plenty of our favorite stars have welcomed kids whose unique names are total standouts, such as Shay Michell and Matte Babael's daughter Atlas Noa or Cameron Diaz and Benji Madden's little girl, Raddix.
Check out some of Hollywood's most unique baby names below!