Violet fungus

A violet fungus was a type of subterranean fungus creature that could be dangerous to adventurers.

Description
Violet fungi were human-sized mushrooms supported by a mass of root-like feelers that allowed them to move slowly to more favorable feeding spots. They could range in color from deep purple to dull gray, or they could be violet and covered in purple spots. They also contained four leafy tendrils. These "tentacles" could apply a secreted poison that caused weakening.

Behavior
Violet fungi could sense nearby motion and would flail their appendages at creatures nearby. They would feed on decaying matter, often from the bodies of creatures that came too close and had succumbed to their poison.

Violet fungi had a symbiotic relationship with shriekers, another closely related fungus species, and often grew interspersed with them in patches. The shriekers' noise would benefit a violet fungus by drawing curious creatures near enough for the violet fungus to poison.

Variants
Cormanthorian violet fungi grew only to around 3 feet (0.9 meters) high. They were often used by treants, who would surround their roots with up to six of these fungi. The fungi's roots tapped into the treant for sustenance, and they helped to protect it against bark-eaters by flailing with tentacles, attempting to rot the predators' flesh.