Fungal Caverns

A mushroom-themed biome found to the west of the Coal Pits and all around the Underground Jungle.

About
The Fungal Caverns, as it appears very early in the game, can be a very lucrative place to visit as it contains much higher tiered wands than can normally be obtained in the Coal Pits. This comes at great risk, however, as the caverns are littered with mid- and late-game enemies like, among others, Turso, Pikkuturso and the lethal Robottikyttä. In addition, projectiles experience moderate deceleration within the Fungal Caverns, rendering some spells like the Energy Orb almost useless as their range is reduced significantly.

The caves themselves are riddled with tight passages, often lined with steel beams that restrict movement and prevent easy digging. Rooms can be completely sealed shut, so without explosives you may find it hard to reach many areas. Growths of fungus are prevalent everywhere, and eating them will cause a wavy colorful effect and distort the music but otherwise have no effect.

Fungal Caverns (Coal Pits)
A small Fungal Cavern to the west of the Coal Pits. Compared to its neighbor, this area contains more items to collect but otherwise has no other points-of-interest.

Around the western edge of the biome, there's an inverted triangle built out of Holy Mountain brickwork, with a glyph resembling an eye. A notebook rests on top of it, reading:

Fungal Caverns (Underground Jungle)
A tiny Fungal Cavern is also present in the very center of the Underground Jungle