If it works with the front facing camera, the phone could be using the proximity sensor for detecting a wave of hand in order to launch the camera lens and immediately take a snapshot. If it works with the rear-facing camera, you can be held or put the phone nearby, and you're just a wave of fire. Options circle, however, it seems quite clear to me. I think it's the power button on the back of the phone, and can be used by LG to launch applications or different functions.

G2 on her, and used LG size buttons to launch applications, and even when she was off the phone screen: launched on the button to raise the volume of LG memo application and reduce the level of sound and camera. Thus, the company is no stranger to add more shortcuts to buttons on the back of the phone, especially given that this is where they claim most users put their finger naturally. The G3, the power button no longer looks like a go right here rectangle shape, but the shape of a circle with a cone interesting.

What if this department acted like a joystick or have had a touch sensor underneath? You could simply spin your finger on it in clockwise and counter-clockwise, and the wheel will launch the application shortcuts or functions on the screen. I may be totally out with the speculation of my own, and options for the department may end up being a feature of the program, something like a criticism of the buttons that appear on the screen to run Google now, but with more applications in baked goods, and this remains to be seen, but I 'd find personally the power button a lot more interesting and unique.