Sphix Fungi

The Sphix Fingi is the cause of the Sphix disease. They are rare, because the mushroom form is just it's final life stage, and they can live for extremely long periods of time in the spore stage, which is invisible to the naked eye, cause they're very small.

The spores feed off magic, which is why they flourish in the Everfree Forest and can survive until maturity out there, because the forest is full of magic sources.
Only in their adult stange, as a mushroom, do they produce more spores. But when a grifix gets infected with spores, they get infected with high quantities, which will soon spread to other grifix. That's why the Sphix disease spreads very easily.
The spores can enter dormant stanges when threatened, which will stop them from absorbing magic, and make them almost imposible to kill. Dormant stages can last very long period of times, so it's very hard to know that a place is infected with spores if they're dormant. As a result, even if the Healer sanitizes the whole place where a Sphix infected grifix walked through, the disease can remerge from that place years later.
The grifix got rid of almost all of the sphix mushrooms in the forest, but because of the dormant spores the disease keeps appearing, and mushrooms sometimes grow outside in the forest too, making it impossible to get rid off.
If a grifix dies of sphix, a sphix mushroom will eventually grow from the gems on their corpse. Burial prevents this, but not completely, cause sometimes the mushrooms will find their way out through the earth. Burning the corpse seems to be the most effective way to prevent mushroom growth, but if the corpse has any dormant spores on it those might still survive.

Creators: Dexter_Tailor, MysteriousShine