365 #106 - A lucky find

This horseshoe sits on a tree behind the wall of a road bridge that I've walked over maybe 60 or 70 times but never noticed until today. (The horseshoe, not the bridge).
Hardly surprising though since it's so worn and was difficult to get a shot of without resorting to some Photoshop witchery (which I didn't).
It's on the far side of the bridge where there's no path. The bridge is a few hundred years old and given how worn this talisman is, I wonder - How long has it been there? Who put it there? Why? And who cares?