Somehow, 10 lonely and disorienting years have passed since the debut of the very first iPhone. To mark the 10th anniversary Thursday, Apple CEO Tim Cook shared a tribute to the late Steve Jobs and the device that "changed the world." Tucked neatly into Cook's post, fittingly, was a nod to Jobs' studied keynote methods.

"Here's to the #iPhone that changed the world, to the man who dreamed it, and the people at Apple who have never stopped looking to its future," Cook said Thursday, sharing a photo of the inaugural iPhone.

As first noticed by Mashable shortly after Cook's tweet started stacking up the RTs, Cook tweeted his tribute message at exactly 9:41 a.m. PT. Also, the device in his photo shows a time of 9:41 a.m.

The significance of that time stems from the exact moment Jobs unveiled the first iPhone. Subsequent Apple advertisements typically followed suit, showing devices with the time 9:42 a.m. Later, that time was bumped back ever so slightly to 9:41 a.m.

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Former Apple executive Scott Forstall explained this in a bit more detail back in 2014. "When the big image of the product appears on screen [during the keynote], we want the time shown to be close to the actual time on the audience's watches," Forstall said, according to the Atlantic. "But we know we won't hit 40 minutes exactly. And for the iPhone, we made it 42 minutes. It turned out we were pretty accurate with that estimate, so for the iPad, we made it 41 minutes. And there you are—the secret of the magic time."

Forstall joined engineers Nitin Ganatra, Scott Herz, and others for a recent Computer History Museum discussion on the iPhone's creation earlier this week. Watch below: