The mycelium lying underground forms partnerships with the roots of about 90% of all the trees and plants which are mutualistic, symbiotic. The mycelium reaches further out and deeper into the soil for both nutrients and water and gives some of them up to the plants in exchange for the organic carbon compounds it needs for survival. Such fungi are called mycorrhizas (root fungi). These mycorrhizas also permit connections between trees and plant life in the shared regions creating what have been called Wood Wide Webs (to paraphrase to the World Wide Web).
This biological system may illustrate the relationships that the Church can or should make with the surrounding environment, such as the secular structures in society.