No kidding.

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.