Need Help Identifying This From An iPhone 6.

Hello, i was changing the Rear Housing Case on my iPhone 6, pretty much transferring everything inside my iPhone 6 into a new Rear Housing Case, i have some knowledge on repairing iPhones but i don't know every little detail about it. (Still learning)

So while i was transferring everything over, this little thing fell out and i can't remember where it was placed or what it even does, this is the first time i've seen this peace, so can anyone help me out and tell me what it does and where it is placed in the iPhone 6, would really appreciate it.

Thanks in advance.

Images below show the peace that fell out.

[img]https://i.imgur.com/FZ5UYbi.jpg[/img]

[img]https://i.imgur.com/1f09eiv.jpg[/img]