What's the chip attached to the back cover for?

[Samba145]

I recently cracked my back cover. I purchased an official looking replacement from Amazon and followed a YouTube disassembly video to replace it.

Once I removed the original back cover I found a circuit board/chip stuck to it's inside surface. It has 2 copper connectors that connect with 2 metal pegs just above the aerial on the main motherboard.

My new back cover doesn't have this chip, although everything so far appears to be working as normal.
Does anyone know what purpose this chip serves?

[Samba145]

I should probably mention it's an Xperia Z2

[Thommo · Accepted solution]

NFC or Near field communication - It's used to sync devices that both have NFC and it allows files to be sent like contacts etc

[Samba145]

Fantastic, thanks for your quick response. I'm relieved that it's not an essential feature, as I'm unlikely to use NFC in future.
Thanks again, Sam