Like the previous object, Antarctic Item 016 lends itself to functioning as an ashtray. In all likelihood, it was.
Who used it? Well, I imagine Shackleton tapping his pipe into it at Cape Royds, splitting the rim at the upper left as he strategized his march to the Pole in 1909. The crack reminded him of ruptured ice, and being a touch superstitious, he brought the ashtray along on the journey to ward off such dangers. Nevertheless, ice crevasses continually hindered his team’s progress, swallowing one of their sledge-hauling ponies and nearly two of their men. Eventually Shackleton came to regard the split ashtray as a bad luck omen, discarding it on the return trek in the Dry Valleys. It was a wise move, assuring his team safe passage from there back to Cape Royds.
Or at least that’s the way I imagine it.