Most desperate, or at least most in-vain, search I've known was for a contact-lens. On a country road with a verge of lank grass.
There we were, I think about six of us, in the Yorkshire Dales for a caving weekend years ago. One of the party had not long transferred to double-glazing after years of wearing glasses – but would swap back to glasses for caving, where inadvertent contact with a waterfall could result in losing contact with contact lens.
She dropped it after the caving-trip, when changing back into ordinary clothes at the roadside.
We all spend ages literally crawling around that verge and asphalt (ironically perhaps, most of the caving itself had been walking!); and yes, we tried using the lowering afternoon sun in the hope that would glint off the lens. No hope.
A couple of us on a trip there again, I think in the following year, had another look but it was out of a sense of duty rather than reality.
So if anyone trying to find a 12BA nut they happened to have dropped on the road through Kingsdale, finds a contact lens instead…