Armillaria ostoyae
Multiple realities
(covers information from several alternate timelines)
Armillaria ostoyae was a type of pathogenic fungus native to the planet Earth in both the prime and mirror universe.
The mirror universe Paul Stamets was infected with this fungus. When he revealed the fungal infection on his arm, his counterpart, Paul Stamets, identified immediately it as Armillaria ostoyae. (DIS: "Vaulting Ambition")