Grimes changes her daughter's name to a symbol and a question.
Grimes explained on Twitter that her daughter's name, "Y," represents "curiosity, the eternal question, .. and such." The Canadian singer and Elon Musk are also parents to 2-year-old X Æ A-XII, nicknamed "X." Grimes previously revealed that they also call their daughter Sailor Mars, a nod to the "Sailor Moon" manga series.