It's time for another rousing round of "Name That Component"!
Today's participant hails from a Bluetooth combo keyboard/mouse, where it detects finger motion across it which the Bluetooth chip translates into relative motion HID messages. It (supposedly) uses an imager of some sort to detect motion of an object that contacts the surface. Does this little beast have a proper name?
(The other side only has a metal key dome under a white sticker which when depressed the Bluetooth chip converts to a middle-click HID message.)