Bought at the flea.
Thanks

I would guess that it is for boring a tapered hole using a brace

Ray

or a feed scoop for canaries

Usually called a bung bore, for boring holes in barrels for the tap and/or plugs. One this small might have been used for furniture making, chair rung holes and such. Maybe a look in Sellens book would answer the question.

It does look just like a bung hole auger though the shoulder is a bit mystifying.  Most I've seen are tapered from the end of the square section.  The size makes me think it is a tap auger rather than a bung hole auger -- for setting in one of the wooden taps at the end of the barrels.