Gare said, in response to ARC's suggested ID as a piece of a window twist-latch:
> OK I see what you're saying but the one you showed had only one hole in it. Mine has 2.
Notice, please, that one of the holes in your brass object APPEARS (maybe it's just the lighting) to be beveled/countersunk, and the other is not. That makes me think the beveled hole was for attaching the twist-catch to the windowframe, and the other "hole" is actually not a hole, but the end of a BROKEN OFF tapered prong/tang which slid under the "catch" part of the latch. I've seen some very old crudely-cast brass ones which have that peculiar shape.
Yes, the object is crudely cast. Notice the casting-mold seam line which bisects the "thumb-push" section of the object.
I've said the object appears to be brass because that's what the patina on it looks like. However, a fresh scrape on the object looks silvery-colored in the photo. I suppose it could be "white-brass"? But we know that colors in a photo can be unintentionally misleading. What do you think the metal is? BTW, does it feel heavy or light for its size?
Nobody has mentioned the tiny number 4 stamped into the object's edge. It might be an ID-clue.
Having said all that:
A photo of the object's other side would be helpful, to cancel or confirm me and AARC's guesses.