Ants and fungi: Leafcutter ants
If you’ve never had the opportunity to see leafcutter ants in action, watch this.
Ants cultivate a particular fungus to feed their young. The fungus is farmed by the ants who provide cut leaves that the fungus decomposes. The ants are sensitive to any parasitic fungus and have a further symbiosis with a bacteria to protect their farmed fungus. The fungus is dependent on the ant to grow, and ants in turn are dependent on the fungal farm. Voila! Myrmecophily.