This unusual metal item appears to be a vintage key-style can opener, used before modern geared and electric openers became common.
The hooked section was positioned against the rim of a tin can. The user punctured the lid and repeatedly levered or “walked” the tool around the edge, cutting the metal a little at a time until the lid could be removed. Similar early openers used a claw-shaped blade and the can’s rim as a support point for leverage.
Some key-style openers also included a slotted end for gripping a metal tab or strip that could be wound around the key and peeled away from specially designed food cans.
The correct answer is: an old-fashioned manual can opener used to puncture and open metal tins.
