Why do mushrooms belong to a special kingdom of living nature? What signs are characteristic for it?

Mushrooms are neither plants nor animals; they were reclassified in the 1960s as a separate Kingdom of the Mushrooms. In a sense, fungi are more closely related to animals than plants. Just like us, mushrooms take oxygen for their digestion and metabolism and “exhale” carbon dioxide as a waste product. Fungal proteins are very similar to animal proteins. The part of the fungus that we see is only the “fruit” of the organism. Mushrooms grow from spores, not seeds, and one mature mushroom decays into 16 billion spores.