Sussurus

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

Description
Sussuri appeared as headless quadrupedal figures of vaguely humanoid, almost apelike 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. These accounts described the creatures as being made up of rotting bamboo. Others said that sussuri appeared to be covered in shards of glass, which encircled the holes that riddled their bodies.

Abilities
The Sussurus had a pacifying dronesong that pacified undead. This sounded like wind blowing gently through trees. They could attack incorporeal undead as if they were made of living flesh. It had blindsight and could detect any undead around it at all times.

Behavior
Susurri were solitary and peaceful creatures. They could sometimes be found in pairs. They 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 susurri 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.

Ecology
Those sussuri that roamed in more tropical climes were commonly in competition with shambling mounds over territory and prey. They could also be found in dungeons and underground passages.

Some sussuri acted as servants or companions to djinn.