KEYHOLES 

While not considered objects per se, keyholes belong to a parasitical variety that relies on real objects in order to survive. It includes shadows, smells, reflections, speed, and others, though keyholes are unique in that they’re able to develop symbiotic relationships with keys.

Sometimes called negative spaces or peep holes, keyholes are often mentioned in mystery novels, and used as metaphors (“the thick, long key slowly penetrated the tight keyhole…”)

Unfortunately, keyholes are now an endangered species. With the advent of magnetic cards, millions of keyholes have lost their jobs in hotels worldwide. The predicted adoption of keyless combination locks might be the next, and final, nail in their coffin.