Okay ... So here I go again out on another limb. (Actually, I'm on three limbs at once).
But this time it comes from my dad who will soon be 88 years old, and grew up on a combination chicken/turkey ranch. (Although, he still calls it the "farm.") Anyway, it was a fairly small farm and they didn't have all the modern advances that the larger commercial farms had. But he does recall that part of his daily chores involved keeping track of how many eggs individual chickens laid. And when a particular chicken began decreasing their expected output, well ... that chicken became dinner.
But in dad's case, he had to keep track of all this on index cards. Plus each and every chicken was banded with an individual number. I'm still not clear as to how all of this was accomplished with there being so many chickens, but dad said it was extremely important to keep track of production.
So "maybe" the item is some kind of egg counter ... and it's even possible the item was fastened sideways with the two bendable tabs to secure it, and the other "flat" tabs were designed to slip an index card underneath so as to make notes.
I know this is far fetched ... but hey, like father like son!
Signed ... "The Chicken Pluckers!"