Fungi on the pigeon loft
One of the pathogens in the pigeons are fungi. In reference books of microbiology it is stated that even though all life on earth had to be almost eradicated, there would still be fungi. They are considered the debris clearing of nature. Mushrooms, for example, are just the tip of the iceberg, to name it that way, because the fungus threads that carry the mushroom as fruit are underneath. We also think of penicillin-producing fungi, discovered by Alexander Fleming, and this invention has caused an immense breakthrough in (animal) medicine. Because surgery became possible because of this invention.