Claire Boucher (known as Canadian singer Grimes) and Elon Musk (CEO of Tesla and SpaceX) welcomed their first child together - Musk's 7th - in May 2020, a son named "X Æ A-12 Musk", which quickly became a trending topic across social media.

Grimes later tweeted a full breakdown of the baby's unusual name:

"•X, the unknown variable

•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, metal rat"

However, the name would have violated California regulations as it contained characters that are not in the modern English alphabet, and was then changed to "X Æ A-Xii".

This drew more confusion, as Æ is not a letter in the modern English alphabet. The child was eventually named "X AE A-XII" Musk, with "X" as a first name, "AE A-XII" as a middle name, and "Musk" as surname.

The other options explained:

• Billion is the name of American rapper Rick Ross' youngest son;

• Musician Frank Zappa named one of his children Moon Unit, and

• Zuma Rock Nesta are the names of the middle son of American singer Gwen Stefani.

More Info: en.m.wikipedia.org