Elon Musk has revealed that he and Shivon Zillis have welcomed a fourth child — bringing the billionaire’s brood to a total of 13 confirmed children.

Zilis, a Neuralink executive, took to X on Friday to publicly announce for the first time the baby

news — and shared the name of their third child, which has until now not been known.

Shivon Zilis shared the news on X Friday. X / @shivon

“Discussed with Elon and, in light of beautiful Arcadia’s birthday, we felt it was better to also just share directly about our wonderful and incredible son Seldon Lycurgus. Built like a juggernaut, with a solid heart of gold. Love him so much,” Zilis wrote, adding a heart emoji.

Elon Musk replied approvingly with his own heart emoji.

It is not known when Seldon Lycurgus was born.

The pair quietly welcomed their third child last year — Arcadia — whose name was revealed in Zilis’ post Friday.

It is still not known exactly when Arcadia was born or whether it’s a boy or girl.

Musk and Zilis conceived their twins using IVF, and Musk has conceived 9 of his children using that method, according to reports.

The mother of four was also a mainstay at Mar-a-Lago last year when Musk set up shop at the president’s Florida chateau in the wake of the election victory.

Zilis, 39, appeared by the SpaceX CEO’s side during President Trump’s inauguration.

Elon Musk is currently leading the Department of Government Efficiency on top of his other businesses. REUTERS
She and 3-year-old twins Azure and Strider were also present for Musk’s meeting with Indian Prime Minister Modi earlier this month.

Maye Musk, Elon’s mother, has previously expressed her love for Zilis on X, in the wake of the public fallout stemming from conservative influencer Ashley St. Clair’s claims that the Boring Company founder is the father of her 6-month-old son.

St. Clair is currently suing Musk for paternity and for custody of the child in Manhattan court.

Musk has an alleged total of 14 children with four different mothers — including six with first wife Justine Wilson, three with pop-star Grimes, four Shivon Zilis, and one alleged baby with Ashley St. Clair.

“Doing my best to help the underpopulaiton crisis. A collapsing birth rate is the biggest danger civilization faces by far,” Musk wrote on X in 2022.