It's a pile of crudely polished bones strung together as a shabby ornament, where Ronan found teeth, finger bones, skulls, and so on, some human, some from unknown wild beasts.
Each bone is covered with bizarre black patterns, like some kind of totem symbol, giving an eerie, evil feeling.
These bone trinkets and the sheep-headed creature's corpse on the ground immediately reminded Ronan of the sheep horn mask he had obtained from the Dark Head of the "Ancient Witch Revival Association"; the styles were very similar, as if they were a legacy from the same civilization.
So, does the "rotten evil" mentioned in the parable refer to the Ancient Witch Revival Association?