The purple toadstool trembles as it emits a piercing scream.

A shrieker is a human-sized mushroom that emits a piercing screech to drive off creatures that disturb it. Other creatures use the fungi as an alarm to signal the approach of prey, and various intelligent races of the Underdark cultivate shriekers on the outskirts of their communities to discourage trespassers.

Large, semi-mobile fungus that wails loudly when approached or threatened

A shrieker, sometimes called a wailing morel, is a large (3' to 5' tall and about the same size across), semi-mobile fungus that wails loudly as a defense mechanism when approached or threatened. Shriekers are found in underground areas such as caverns and dungeons. They are found in a variety of pale colors, most commonly white, gray, lavender, or red. This monster does not attack directly; rather, its shrieking tends to attract the attention of other monsters in the nearby area. Movement or light within 10 feet, or causing any damage to one, will cause one to wail for 1d4 rounds. In game terms, the GM should generally roll a wandering monster check each round that this monster wails.

Giant, subterranean mushrooms that can creep around slowly.

Large, semi-mobile fungus that wails loudly when approached or threatened

Shriekers are mobile fungi that wander around quietly underground soaking up moisture. They are the favourite food of purple worms and shambling mounds. They give off an ear-piercing shriek whenever they detect light within 30-ft or movement within 10-ft. Shriekers will continue to shriek for 1d3 rounds, with a 50% chance to attract a wandering monster each round.