Weird Fungus is an odd pink material that can be found in the Fungal Caverns. It can be easily walked through, although it does not provide air and can cause suffocation if one remains inside it for too long.
Unlike most materials, it will slowly grow upwards, forming usually slender columns. If a moderate amount falls down due to the ground beneath it being destroyed, the movement seems to accelerate its growth, quickly generating massive spires of pink fungus. Pouring it from a Powder Pouch from great height, can create massive towers of fungus.
If ingested, the player will receive the Tripping status effect, which will cause visual and aural distortions. If further amounts are ingested, the distortions can increase, and at high levels of the Tripping status, strange eyes will open and close at random in the background, with an accompanying sound effect.
When gaining at least 180 seconds of the Tripping status effect, a Fungal Reality Shift will occur.
Green Fungus is a rarer variant of Mystery Fungus, and behaves in a very similar fashion.
Mystery Fungus behaves very similarly to Weird Fungus, including the effect of ingesting it, with the additional quirk that it will convert many other liquids and powders into more of itself quite rapidly. It can be created by mixing Toxic Sludge, Fungus Blood and sand.
Blue Fungus presents as blue mats of mycelium, eventually producing blue fruiting bodies, however it is mainly present as a portion of the terrain in the Fungal Caverns. The fruiting bodies of the blue fungus drop glowing fungal spores at their bases which can be collected with in the Powder Pouch after which the mushroom falls over and disappears. The spores will produce blue fruiting bodies if they are scattered on the ground which mature rapidly. As it is a static material, it cannot be ingested, unlike other kinds of fungus.
The Forest where the game begins features brown, salmon and sky-blue mushrooms on the surface and in caves. Smaller mushrooms also appear in the Mines. These are background elements and only become interactive if dislodged by damage. Eating them will inflict Food Poisoning instead of Tripping; however, they may be "ground up" into fungus blood in much the same fashion as worm corpses.