Death
As a concept, death has demonstrated extraordinary persistence throughout the estimated 300,000 years of human existence. Attempts to eliminate it through alchemy, medicine, and technology have uniformly failed. Despite humanity's considerable investment in extending life, death's durability remains uncompromised.
The concept shows no signs of degradation, obsolescence, or market fatigue. If anything, advances in medical science have only heightened awareness of mortality's inevitability. Death, it appears, is genuinely eternal—a claim few entities can legitimately make.
Rubber Duck
Modern rubber ducks, typically manufactured from polyvinyl chloride, exhibit respectable material durability. Laboratory testing reveals resistance to water damage, reasonable temperature tolerance, and immunity to the pruning that afflicts human bathers. A well-maintained specimen may survive decades of service.
However, rubber ducks face several durability challenges. Ultraviolet radiation causes yellowing and brittleness. Mould colonises their hollow interiors with disturbing enthusiasm. The species is also vulnerable to enthusiastic canine attention. Material durability, while adequate, cannot approach the conceptual immortality of its competitor.