Necromorph Apocalypse

Necromorphs are the main antagonists of the Dead Space video game series. They are human corpses (or other organic beings) reanimated and transformed by a recombinant alien infection.
Key features (Updated to 2025)
Origin: The mutation is caused by electromagnetic signals emitted by alien artifacts known as Markers. These signals affect dead tissue and also induce madness or dementia in nearby living beings.
Transformation: The process is violent and rapid. The host's bones break and rearrange themselves to form claws and sharp limbs, while the organs transform into new, extremely strong musculature.
Weakness: Unlike traditional zombies, headshots and body shots are ineffective. The only effective way to eliminate them is through strategic dismemberment (cutting off their limbs).
Purpose: Its sole objective is to kill living beings to generate more biomass. When there are enough corpses, an event called Convergence begins, which unites all the necrotic matter to create a Sister Moon, a planet-scale necromorph.
Common types of Necromorphs
Type of Characteristics
Slasher The most common one, with two long blades sprouting from its shoulders.
Leaper moves by hopping and uses its bony tail as a whip; it has no legs.
Lurker Created from babies or fetuses; fires projectiles from tentacles on its back.
Infector: A manta ray-like creature that injects the virus directly into fresh corpses to transform them.
Brute A massive, armored mass of several bodies that overwhelms the player.

You're probably referring to the Markers, which are the fundamental artifacts in the Dead Space universe responsible for the creation of the necromorphs.
Although "sphinx" and "effigy" are different words, in the context of the game, only "Effigy" is used to describe these obelisks of alien origin.
Relationship between Effigies and Necromorphs
Origin of the infection: The Effigies emit a constant electromagnetic signal that alters the genetic code of dead tissue, reanimating it and transforming it into necromorphs.
Effects on the living: In addition to creating monsters, the Marker's signal induces madness, paranoia, and hallucinations in nearby living beings.
Purpose: The ultimate goal of the Marker is to collect enough biomass (corpses accumulated by the necromorphs) to initiate a Convergence event, which gives rise to a "Sister Moon" (a planet-sized necromorph).
Types of Effigies
Black Effigy: The original artifact found on Earth (Chicxulub crater).
Red Effigies: Replicas created by humans through reverse engineering, like the one found on planet Aegis VII in the first game.