Zarmeshs Brain is a massive petrified head of a disembodied thinker. This creature was used by the primordials to crunch numbers, keep records, and serve as a living archive for all the activities of the primordial offensive. This offensive spanned battles and wars across the Mortal Systems. The size of the conflict, the Dawn War, was so immense that these disembodied thinkers were created from thousands of brains merged together in some hideous dark experiment.
Typically, one brain showed dominance over the others, slowly consuming the others, and adding their brain power to its own. The disembodied thinker was then exposed to some force, perhaps psionic, which lobotomized the brain to a point where it was subservient to a primordial master.
Zarmesh was a disembodied thinker that served the Master of Tides. Zarmesh was turned to stone in one of the battles of the Abyssal Release - a conflict between the primordials and the demons that coincided with the weakening of the primordials in the Dawn War.
In the God Era, angels found the petrified Zarmesh in the ruins of Mughakh-Gol. They moved this potentially dangerous creature to a swamp of Dulpathâra called Naikad. Moving him, or it, to the swamp was a calculated move by the Wardens of Bal-Kriav. They made use of the psychic disturbance emanated by the petrified Zarmesh to keep Naikad's earth elementals from breaking the swamp's grip.