Introduction to the underground forest: is a large area of stalactite pillars, some are large and some are small, some are thick and some are thin, some are like bushes, some are like towering trees, alternately dense and dense, just like a virgin forest. Of course, it is tens of thousands of years older than the living plant fossils of Davidia involucrata, Metasequoia, and Ginkgo left over from prehistoric centuries on land.