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What is happening in the mind of Elon Musk? It's one of the great questions of our time, and now we have one less portal into the entrepreneur's head space -- his Instagram account appears to have gone up in a puff of smoke.

It's not clear when exactly Musk's account was last active, but internet archive the Wayback Machine shows a snapshot from July when the account listed 8.2 million followers and 226 posts.

A representative for Musk declined to comment.

Last week Musk spoke to the New York Times about his "difficult and painful year," after tweeting about potentially taking Tesla private. Since tweeting about his plans, his popular social media accounts have been under more scrutiny than ever.

Twitter has long been Musk's favorite social platform for expressing himself, but he hasn't used the platform to explain his sudden disappearance from Instagram. Up until now, Musk has seemed at home on Instagram, but there's precedent for him deleting social media accounts. In March of this year he deleted the Facebook pages for both Tesla and SpaceX.