God I love the Fishers. Where else do you get such mystery clips? Maybe it is a dead bat wedged in there?

Brad it is best not to ask questions and just trust.

Assuming there is a prize: my guess is an ancient rusted (pre lost arrow?) pin that someone reslung and then bashed farther in using another pin as a piston. (Veeery clever for that guy, veeery spooky for those ever after.)