Sussurus

A sussurus (NaN undefineds NaN undefineds ), also known as a susurrus, headless droning ape, or singing ape, was a creature with an undead-pacifying dronesong.

Description
Sussuri appeared as headless quadrupedal figures of vaguely humanoid, almost ape-like shape. They had an exoskeleton filled with small gaps that drew in sustaining air, which created the creature's signature dronesong.

Some sages considered sussuri to be a form of plantlife, distantly related to the shambling mound. Their accounts described the creatures as being made up of rotting bamboo. Others claimed that sussuri appeared to be covered in shards of glass, which encircled the holes that riddled their bodies.

Abilities
By constantly inhaling air, sussuri generated a dronesong which sounded like wind blowing gently through trees. This sound could render certain types of undead peaceful and torpid, similarly to the effects of hold undead, in a phenomenon which was known as the "sleep of the dead". Some sussuri were able to affect the living in a likewise manner, sometimes knocking unsuspecting adventurers out for as long as half a day.

Sussuri achieved a form of blindsight by detecting disruptions in the airflow travelling through their exoskeletal tubes, thus rendering them immune to most conventional magical means of impeding or evading sight or hearing. However, they could apparently be blinded by fog clouds and similar magic.

Behavior
Although typically peaceful, sussuri became agitated around any undead and those carrying torches, wielding flame or otherwise tainting the air they needed to survive. Otherwise, they kept to themselves.

Combat
In combat, the sussuri used their claws to tear their foes to shreds. It could grapple it's foes after it had dug it's claws in. Against undead foes, it's dronesong caused undead to become unable to move, pacified by the sound. Any creature that attacked the sussurus with handheld weapons, teeth or claws would cut itself on the aberration's jagged glass-like skin.

They could attack incorporeal undead as if they were made of living flesh.

Sussuri were generally vulnerable to plant-affecting spells, albeit less so than most plant creatures. They were rumored to be especially susceptible to the effects of warp wood.

Ecology
Sussuri were typically solitary creatures, though they could rarely be found in pairs.

Some sussuri acted as servants or companions to djinn.

Habitats
Sussuri were known to inhabit a wide variety of temperate-to-tropical environments, but some populations specifically required a hot, rainy, plant-rich environment. Others, however, were content to roam underground areas, such as dungeons.

Those sussuri whose territories overlapped with those of shambling mounds often violently competed with their evolutionary cousins over territory and prey.