The thing that I find most fascinating about fungi is that on a basic level they are hunter gatherers like us. They hunt for plant protiens but more notably the oyster mushroom hunts small worms in the soil called nematodes, it uses a lasso type snare to catch and digest the worms, I find this fascinating. Also when trees develop their cellulose partly converts to lignin, this hard substance is what gives trees their strength but is undigestable to all animals except certain fungi, how cool is that!