Mystery sensor found under the dirt?

While repaing a leak in my windshield washer tank I clean as I go, I found this shiny round thing with wires in the back? It is on the passenger side only by the air vent to the wheel well. Can some one tell me what it is or is for?

David, see the answer to your ‘gizmo’ thread.

Sorry abuot that somehow I posted it twice.