Motorola's Nexus 6 was originally scheduled to feature a fingerprint sensor where the dimple is located at the back, but the idea was ultimately foiled by Apple. Motorola was working on fingerprint recognition with a company called AuthenTec, with devices from as far back as 2011 featuring the technology. However, Apple acquired AuthenTec in 2012 for $356 million to use the technology in the Touch ID sensor, which meant that Motorola had to look elsewhere.
According to former Motorola CEO Dennis Woodside, other options didn't quite cut it, meaning that the feature was left out from the Nexus 6:
The secret behind that is that it was supposed to be fingerprint recognition, and Apple bought the best supplier. So the second best supplier was the only one available to everyone else in the industry and they weren't there yet.
Early prototypes made by AuthenTec, dubbed FingerLoc, were not as elegant as the final Touch ID sensor, but the technology itself was promising enough that Apple acquired the vendor in July 2012. The inclusion of Touch ID made possible services like Apple Pay, which has been continually gaining traction since its launch last year.
While Woodside went on to add that the fingerprint sensor "wouldn't have made that big a difference," an in-depth look into the Nexus 6 firmware files revealed that support for the sensor was removed at the last minute, and that Google was working on authentication and payment-related services that tie in with the sensor.