Weird screw

[Gregory J. Wolters]

I just had the timing belt / water pump work done on my car.  86 4KCSQ,
166K miles.  Funny thing was that the mechanic found a large screw
bouncing around in the timing belt cover area.  It had taken several
gouges out of the timing belt.  Said he didn't know where it came from.
The screw is clean (not greasy), 1 1/8" long with very course threads, a
normal screwdriver slot / hex head top, tarnished silver in color.
Looks kind of like a heavy duty sheet metal screw.  I quickly checked
the Bentley with no luck.

Has anyone had a similar experience?

TIA

Greg Wolters
Nevada City, CA
86 4KCSQ