These crustose lichen attach themselves to rocky areas by sending part of the fungal structure a few millimetres into the rock. Lichen is able to secrete an acid onto the surface of the rock. Over a period of time, the acid begins to break down the rock. The lichen, therefore, helps create an environment where other plants can begin to grow and animals can live. This is why the crustose lichen is known as a pioneer plant.
Pioneer plants are plants that help create an area where other plants can take root and grow.
It often joins the crustose lichen and also helps to weaken the rock. As these lichen die, they help form thin pockets of soil on the surface of rocks. This lichen is often found with larger plants like mosses. This type of lichen is sometimes called reindeer moss. It is called this because it is an important food source for reindeer and caribou, especially in the winter.