Not happy, Jan.
Could have been anywhere along about 15km of rough gravel road, a lot of it in blue metal - chances of spotting a little black plastic square marginal to none from the drivers seat of a car. And no time or energy to ride it... I didn’t have it on either - if I had I would have waited for dark and gone looking for it!Bugger about the rear light. Maybe retrace your ride. I've found stuff I've lost.