The state’s law prohibits names from containing any digits, so the couple was forced to replace the 12 with roman numerals.
The boy, who is only 11 months old, is now named X Æ A-Xii, which is pronounced X Ash A Twelve.
Explaining the unusual choice, Elon Musk said on the Joe Rogan Experience podcast the name is a call back to the “coolest plane ever”.
He said: “It’s just X, the letter X, and then the AE is like pronounced ‘ash’.
“Yeah, and then A12 is my contribution. Archangel 12, the precursor to the SR-71, coolest plane ever.”