Mystery chip in slimstack connector - smallest I've ever seen!

It's been a while since I did this iPhone 4(?) repair but going through some old photos I came across this super-closeup of a tiny chip that I wouldn't have even seen if it hadn't glimmered like a bit of loose micah. I don't remember if this was the connector for the screen or what, but I do know that the replacement part (are they ever oem?) didn't have it. I've never seen anything like it. It reflects rainbows like a cpu wafer and it's under glass, apparently. Anyway, didn't find anything on the internet anywhere, wonder if anyone has some info.

ultratech