Bone collectors are a species of wild animal that populates the worlds of The Darkness, primarily Umbra. No one knows much about them since they exist in complete darkness; however, they’re predators, very fast, and only interested in extracting and eating bone.
They’re considered scavengers among members of The Darkness, who are powerful enough to usually ignore them (and many of whom also lack bones, so). Of course, anyone without those powers – such as folks who need light to see – are in big, big trouble.
They take bones. They eat bones. They keep bones. There are tales of immense, intricate palaces of bones, hidden deep underground, but that’s just rumor, right?