Its a nickel.

i name him fred

Look carefully at the hole: it was fastened with a lockwasher at one time. So that would imply a machine screw was used. And you also now know what the top surface was - in this case, the angled part wraps downward over something as shown in your second photo.

The underside shows an oxidation line where it overlaid some other component.

The slot must have been meant to clear something, otherwise it wouldn't be there. Possibly a rollover wire since the slot seems too narrow to fit the thickness of bracket steel and other mechs; OTOH it almost looks like it could "just" slot two of those same pieces together if you had them.

These clues might help narrow down its attachment and purpose.

Looks like part of a key lock mechanism?

John

I almost agree with this, but think that the screw hole is too small. I have seen some lock mechanisms use this type of "bar". I had wondered why part of it was curved, perhaps for strength?

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