green plants that grow tenaciously in a small rock cave

green nature leaf soil wildlife rock flower plant tree water grass animal insect invertebrate branch geology autumn reptile plants that grow tenaciously small cave archeology background building features calcium cave ology caves color images crystallization destination europe blank buildings cave explore caverns china corridor dark dirty european culture geology green guilin horizontal illuminated limestone maze mysterious narrow natural natural country parks nature paleontology photography places interest plants poland rock formations rocks rough stalactites stalagmites tourism travel tunnels underground unmanned vertical composition walls weird zen