Elon Musk has confirmed that he and former partner Grimes have a third child together – and its name is just as unusual as its siblings`.

The child is called Tau Techno Mechanicus, the technology billionaire wrote in a post on X (formerly Twitter) on Sunday.

Musk, who owns the social network, was responding to a post from entertainment news account Pop Base, which named his and Grimes` three children as “X Æ A-Xii, Exa Dark Sideræl Musk, Techno Mechanicus.”

The child`s existence had been kept a secret until recently.

Musk and Grimes broke up in September 2021, but the Canadian singer – born Claire Boucher – has described their relationship status as “very fluid.”

In a March 2022 interview with Vanity Fair, she revealed that Exa Dark Sideræl Musk was born via surrogate in December 2021.

Although the couple apparently had no intention of announcing the birth of their second child, nicknamed “Y,” Grimes shared the news after Vanity Fair journalist Devin Gordon overheard a baby crying.

Grimes and Musk had a son named XÆA-Xii in May 2020.

Musk, 48, has five children from her previous marriage: twins Griffin and Vivian, and triplets Damian, Saxon and Kai.

He has previously expressed concern about Declining Birth rates.

"The U.S. birth rate has been below sustainable minimums for almost 50 years," Musk wrote on Twitter in May 2022.

And in July of the same year he reaffirmed his position.

"I am doing my best to address the depopulation crisis," he posted. “The declining birth rate is the greatest threat to civilization.”