There’s plenty that’s striking about Phoroncidia rubroargentea, a species of spider native to Madagascar, starting with their size — at just three millimeters, they’re barely larger than a few grains of salt. But the reason they caught Sarah Kariko’s eye had to do with their color. Unlike many other species, which gradually see their color leach away when preserved in ethanol, the tiny spiders dazzled with brilliant, shimmering red and silver, even after decades in ethanol.