Many harmful or infections fungi (or the spores) are not visible to the human eye while unassisted by a microscope. Sometimes they are, so there is not a definitive answer to the question as posed.
fungus
A kind of fungus.
There are fungi such as mycobiont, red fungus, and yellow fungus!
Mushrooms are a kind of fungus that people like to eat.
its not a fungus! Its called poison ivy. Why are you touching fungus...stupid.
the fruit
It is difficult to determine the "worst" fungus as this can vary depending on context. However, some fungi such as Candida albicans, which can cause serious infections in humans, are considered particularly problematic.
It is grown as yeast is a kind of fungus.
It is a fungus.
AntiBiotics kill bacteria, not fungus. To kill Fungus, An Antifungal Would have to be used.
Category 5 is the worst.
I advise you to see a dermatologist.