The Black Marker is an alien artifact, discovered on Earth by the Earth Government in 2214. It was then hidden to discourage alien belief, yet was brought to public knowledge by Michael Altman, who had been contracted to research the Marker nearly 200 years prior to the events of Dead Space. It is the source of the codes the Earth Government copied to create their own Markers, which have the same devastating effects as the original.
The Black Marker was found by Michael Altman and a team of researchers in the asteroid impact crater off the coast of the Yucatán peninsula in Mexico. It was thereafter concluded that the Marker landed on Earth along with an asteroid that may have caused the mass extinction of the dinosaurs approximately 65 million years ago. The existence of the Black Marker had been known to the locals that lived near its resting place for generations, but was never spoken about to outsiders and was referred to as the "The Tail of the Devil." The locals tend to cross their index and middle fingers when speaking of it.
Altman's discovery spawned a religion, known as Unitology, that grew faster than any other religion ever formed on Earth. According to official sources, Altman was mysteriously assassinated by the government to silence the truth, and thus he became a martyr figure to the religion's believers. In reality, the government had him killed by a Necromorph created due to the Marker, so that they could intentionally use him as a martyr figure for Unitology. The Black Marker is revered by Unitologists as an immensely powerful holy object, which God sent to show that death is not the end. Various tests on the Marker led to it being reverse-engineered; the result was a functioning copy known as the Red Marker.
The Black Marker was classified government property, and although Unitologists worshipped it, they only appear to have had pictures and possibly the leaked vidlog from Altman to base their beliefs on. As most data was classified, their conjectures and the comments of Altman caused irrational, hysterical ideas about the Marker to gain momentum. The Unitology religion offered vague promises of immortality, backed up by apparent scientific credibility, which excited many previously purposeless and depressed people in the dry and impoverished world.
The Church of Unitology, of course, always wanted to get its hands on the Marker (which was the reason they were so excited by the Marker found on Aegis VII), though they seem to have had access to the Red Marker prior to the events of Dead Space; this suggests they had agents in the government. Altman, after seeing the horrifying effects of the Marker, sank it along with the floating facility it was housed on, so it could never cause harm again; its status is currently unknown. Two Earth Government officials who supervised the project, Markoff and Stevens, made sure that the data of the Marker was copied so that they could make their own Markers for more research.
The Black Marker's influence is similar to the Red Marker's. It was revealed in Dead Space: Martyr that there is a different force surrounding the Black Marker than just the ability to cause madness in humans. Altman thought that there was something in the human mind that caused the hallucinations - a kind of defense mechanism that is activated in the human brain when in the Marker's presence. Altman was not immune, but he was able to resist the madness caused by it. It is possible that in all of these cases, there are actually two forces working on people's minds; this is shown when many people in Dead Space: Martyr claim to hear two voices. One of these voices tell the people to kill themselves, while the other appears to be trying to protect people from the Necromorphs by telling them to run, or in the case of Isaac and the Red Marker, manipulating them to help the Marker stop the Necromorphs.
The symbols on both of the Markers apparently represent DNA, and the double-helical structure of the marker itself alludes to this.
- The Black Marker was completely unaffected when the piece was taken from it; however, it seemed to "think" it wouldn't be because it made one of the people, on the submarine taking the piece, go insane and kill both himself and his partner and write symbols all over the walls with their blood.
- The piece that Michael Altman owned was copied by Harmon and used in combination with the information saved from the sinking platform that contained the Black Marker to make the Red Marker.
- According to Michael Altman's analysis of the core sample taken from the Black Marker it has several unusual physical properties. Its structure is smooth both outside and within, the edges featuring a strangely uniform mineral vein structure. This substance is like granite in appearance but almost as hard as corundum, one of the hardest minerals on Earth. Due to the robustness of the Red Marker, it can be assumed all other Markers based on the black one are physically similar as the Red Marker could not be destroyed easily either.
- The Red Marker appears to be the color red because the element Bismuth was used to replace certain elements present in the duplication of the Black Marker.
- The various Markers have conceptual as well as some physical resemblance to the Monoliths from the Space Odyssey series by Arthur C. Clarke, who also served as the inspiration for Isaac Clarke's surname.
- The Chicxulub crater is a real-life crater. True to its location in the book, it is the crater caused by the asteroid impact that supposedly wiped out the dinosaurs. In the book, the Black Marker was carried by the asteroid that hit Earth 65 million years ago.