Vegetation grows on and in everything in the park. Large rocks and boulders become covered with algae and lichens. Their metabolic byproducts slowly decompose the stones creating a minute layer of nutrients. Mosses soon sprout up adding to the nutrient layer. In time, a soil layer is created from the decomposing stone sufficient to support ferns and eventually a seed from a tree will take root. It is not unusual to see stones completely in the grip of large tree roots.