Shriekers were large, Human-sized mushrooms that thrived in dark and damp places, most often the Underdark. They resembled Violet Fungi but lacked mobility and the poisonous tentacles of their kin. Instead, shriekers defended themselves and lured potential prey by releasing a piercing wail that lasted several seconds whenever they detected motion or light. Though they could not kill or move on their own, shriekers often grew in patches alongside violet fungi, relying on them to bring down creatures drawn by their cries. They fed on the decay of organic matter left behind, adding to the slow recycling of life in the depths.
Beyond their role in subterranean ecosystems, shriekers were also used by others who understood their strange nature. Some Underdark dwellers planted them as living alarms to detect intruders, while certain cults cultivated them as a food source despite their poisonous flesh. Other creatures, such as Hook Horrors and Shambling Mounds, could feed on shriekers without harm.