I think you'll find it's a 'Memento Mori' wax seal stamp missing its handle. With a bit of enhancement to your picture, I believe I can see the word "TIME" (at the 'top', as presented here) but in reverse letters, as would be the case for a seal stamp:
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Here's the positive impressed result from a similar one, with the hourglass and the inscription "TIME IS SHORT". This one was said to be Georgian, but with no evidence to support. Victorian would be more likely, I think.
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