Elon Musk and Shivon Zilis have welcomed their fourth child together

Shivon shared on X: "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."

Musk, 53, commented on the post with a heart emoji.

Elon and Shivon's twins were born just weeks before he and his on/off musician partner Grimes welcomed a baby girl, Exa Dark Sideræl, via a surrogate.

Nearly, two years later, Grimes took to X to share about the unusual family dynamics and to stress that she and Shivon had no ill will towards each other.

She wrote: "I spoke with Shivon at length finally, which was long overdue. Plz don't be angry at her! We respect each other a lot and we're excited to become friends and have the kids grow up together.

"Communication about the twins wasn't handled super well in the past, but I now totally understand what happened and totally forgive the situation. Women are so often pitted against each other. Speaking with Shivon, it's very evident she's an amazing human and we both just want what's best for our kids."

Shivon responded: "At the end of the day it all ended up for the best! Thank you for taking the time to really connect and understand each other. So glad we had such a wonderful talk, was insanely overdue. You're a total b***** and I respect you very much as well. I can't wait for kiddo play date and congrats on baby Tau as well!"