The below red one is not mushroom, but Galeola septentrionalis, a sort of orchid. They have no leaf and no chlorophyl.
Answer is that they take nutrition from mushroom as if they are parasite.
After that, the revenge begins. Poor invaders stock the nutrition in their hyphae. However, Galeola septentrionalis does not allow them to do so and take the nutrition from them instead until they are finally exhausted. It is very interesting that Galeola septentrionalis apparently mimics to be easily conquered by the mushrooms. It is really fatal attraction.