Beeber

The beeber is a worm that lives in the ear cavities (preferably the tympanum) of mammals, with its ecological niche being the the wax produced by such ears. Persons infected with this ear worm often experience a low rhythmic hum from the beeber's movements, eating, and, particularly, mating calls, which, despite its low volume, can cause psychological stress (and, interestingly, even more so among undead people).

It is believed the beeber was endemic to Amerada and South Mondesia, before being deliberately introduced to the rest of the world.