One of the most stunning elements of the first iPhone, which turns 10 years old today, is that it jettisoned the idea of a physical keyboard in favor of a software one. The idea, in hindsight, feels like a no-brainer. But during the iPhone’s development more than a decade ago, the idea of an on-screen keyboard was a radical concept that ultimately had a colossal impact on the future of software interface and smartphone design.

To commemorate the event, the creator of that software keyboard, human interface designer Ken Kocienda, posted a photo of two early iPhone prototypes he used to develop the keyboard. In a neat little tidbit of tech history, it appears Apple’s Project Purple team, the clandestine division responsible for early iPhone development, called these units “Wallabies,” for reasons unknown.

Here are two iPhone prototypes. We called them Wallabies. I used these devices to make the software keyboard. pic.twitter.com/qbofBL3RUt — kocienda (@kocienda) June 29, 2017

I kept those devices in my desk drawer for years. When I left Apple, returning this hardware was tough, like saying goodbye to old friends. — kocienda (@kocienda) June 29, 2017

The devices themselves are absolute monsters, as rightly expected of a smartphone prototype of 12 or so years ago. The bezels are gigantic and the devices themselves look very uncomfortable to just hold in one hand, let alone be used to develop a revolutionary software keyboard on.

Still, it’s remarkable to see just how much similar these early gadgets resembled both the consumer-grade iPods of the time and the eventual first-generation iPhone. It took leaping over a number of pivotal mental and technical hurdles to marry a high-quality display with a capacitive touchscreen and an unprecedented multitouch interface.

Yet the simplicity of just removing that iPod click wheel and expanding the screen so it could fit a software keyboard is pretty astounding. In hindsight, it’s really simple and yet, at the time, it was probably extraordinarily difficult to your wrap your head around.

A look back at the first iPhone