The Apple M7 motion coprocessor is Robin to the Apple A7's Batman. Watson to its Sherlock. Chewbacca to its Han Solo. You get the idea. It's something that helps take some of the busy work off the hero's back. In other words, it's the sidekick. In this case, it's also a very specific one. On the iPhone 5s, iPad Air, and Retina iPad mini, it does exactly what its branding implies — it collects and keeps all motion data on the device.