Mushrooms Dominate the World

I was bored in class and wrote a story about the Mushroom Dynasty. Oh my god, a hundred-word synopsis for a short novel is too much. Shocked that mushrooms rule the world. A terrifying fungus is behind this. Is the iron-eating beast's past so legendary? If they are so powerful, why have they disappeared now? What is the truth of the world? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.