(Photo: Barna Páll-Gergely and Nikolett Szpisjak/ZooKeys)
This is the Angustopila dominikae, a resident of Guangxi Province, China. At 0.86 mm across, it's the smallest known land snail in the world. It's 1 of 7 new microsnail species discovered by Dr. Barna Páll-Gergely and his colleagues in Guangxi Province. They published their findings in the journal ZooKeys. It's a landmark discovery, but Páll-Gergely admits that they don't know what evolutionary advantage such a tiny size could offer the Angustopila dominikae. The Guardian quotes him:
We cannot explain their size by adaptation to the environment. For very tiny insects we can guess the evolutionary reason why they evolved like that, but in the case of snails it is much more difficult. The whole family of species are all very small and their common ancestor, which lived maybe 60 million years ago was also very small. Since then this very tiny species survived somehow in different geographical areas and under different climates.
-via io9