The iPhone is 10 years old today, as Steve Jobs launched the game-changing gadget exactly a decade ago.

Since then it has become one of the defining pieces of tech of the 21st century, and has inspired many other tech firms to develop their own smart phone technology. But in a rare glimpse into the secretive world of Apple - where firebrand boss Jobs once promised to fire anybody who revealed details about the new device before launch - an alternative operating system can be seen in this leaked video clip. The footage shows wheel-based system that was developed from the original iPod design, and would have seen users scrolling through options using the wheel familiar from their amazingly popular MP3 device. The footage was posted by Apple insider Sonny Dickson, who says "Not much was known about alternate versions of the iPhone until now. "Despite carrying a similar design, the phone itself is extremely different from the iPhone we know today," he adds. "Instead of the modern touch-driven interface we now call iOS, it featured an operating system dubbed “Acorn OS” (this was an internal code name, and it unclear if it would have kept that name if it had been released), which is derived from the acorn shown on boot. "It presents an on-screen click wheel, which took up the bottom portion of the screen, and on the other half of the screen, a UI identical to the one found on the beloved iPod." Former Apple employee Tony Fadell - known as the "godfather" of the iPod - also worked on the early iPhone designs and confirms the rotary wheel was an option at first. "We were turning it into a rotary phone from the sixties," he told the BBC. "We were like, 'This doesn’t work! It's too hard to use'." Sadly, we will almost certainly never see a version of this prototype given that Apple actually employs people to destroy prototypes that don't make it to market.