The Rings of the Dead are artifacts that can produce Zombie Powder, a substance able to both reanimate the dead and bring eternal life to the living. Though the Rings' creator remains unknown, they are sought after by many people, known as Powder Hunters, for their incredible power. There are 12 Rings in total, and only three have been given confirmed locations.
The Rings of the Dead appear as normal rings, with varying decals on top, though the decals are mainly just for show, and do nothing to enhance the Rings' power. In actuality, the Rings appear very ordinary; on occasion, the Rings of the Dead are mistaken for regular rings, which can lead to disastrous results (Emilio Getto, who thought that one of the Rings of the Dead was a normal ring and was rendered comatose by it when the Ring latched itself onto his brain). They also seem to have some consciousness, as Gamma once said "It's jealous that one of it's brothers has already found a place to feed."
Powder Hunters are people who want to have the Zombie Powder, and so they search for the Rings. Usually, a Powder Hunter has a significant amount of strength/power and is rendered a criminal of, at least, a B-rank (because they often do things against the law to get their hands on a Ring). Because there are only twelve, there are often battles between Powder Hunters for the opponent's Ring(s). Powder Hunters can be divided into two classes: the gang leader-class and the loner-class (do not take literal). The gang leader uses his own power to gather criminals for his gang and then he uses his gang's strength to get his hands on as many Rings as possible. An example of a gang Leader is Ranewater Calder and Baragne Balmunk. The loner, on the other hand, searches for the Rings himself, perhaps with a partner. They travel the world and aren't interested in underlings or power in the underworld. The prime example of a Loner is Gamma Akutabi.
List of Powder Hunters
When all 12 Rings are brought together, they are said to be able to produce the substance Zombie Powder, able to grant the living eternal life and also able to bring back the dead. It is unknown if the Powder has ever been produced in the past, though if it has, the Rings were scattered after its production.
In addition to being able to produce Zombie Powder, the Rings themselves are embedded with a parasitic power; upon coming in physical contact with a host, a Ring will burrow its way into that person's body and root itself in their brain, where they will feed off their host's "life force" until the person dies or the Ring is removed from the host's body. In some cases the Ring attacks the host violently, such as in the case of Gamma Akutabi when he demonstrated the Rings' deadly power in front of Wolfina and Roscoe; the Ring sprouted miniature arms and literally dug through his arm. In other cases, however, a Ring will leech onto a host discreetly and without any blood, such as when a Ring invaded Emilio's body and Emilio barely even noticed.
Because of the Rings' ability to eat anyone who comes in contact with them, some people have gone through extreme measures to prevent themselves from becoming a Ring's prey. Gamma Akutabi uses his metal arm to hold the Rings, while C.T. Smith always uses a glove when handling one. Wolfina, however, was able to smack a Ring away from Gamma with her bare hand, perhaps implying that it takes a Ring a short while to react to a source of life nearby.
After finding and invading a host, a Ring will protect its source of food by attacking and occasionally latching onto anyone who threatens the host or the Ring itself. When Emilio Getto was brought to Nazna Gemini for treatment, the Ring's arms emerged and attempted to attack her. However, she subdued the Ring's arm by pinning it to the table with multiple scalpels.