Precursor (Awakening)

The Precursors are an extremely technologically advanced race originally native to the Pinwheel Galaxy. They were classified as "Transsentient" beings by the Forerunners, having the ability to travel among galaxies and accelerate the evolution of intelligent life. Originally believed to have been driven from the Milky Way galaxy by the Forerunner Ecumene, the Precursors in reality withdrew willingly, never defending themselves and simply marveling at the sheer violence the Forerunners were capable of. Though they sustained heavy losses, the Precursors' numbers began to recover over the succeeding ten million years. Eventually, most of the surviving Precursors would adapt their physiology and essences to form the central intelligence of the Flood species, forming the initial framework of the Gravemind. At least two residents of the Milky Way, the Primordial and the Augur, would remain unaltered following the creation of the Flood, and oversee its uprising against the Forerunner Ecumene.

Description
The Precursors' anatomy was unique. Their inner structure was composed largely of form-changing cells capable of rapidly alternating between functions and adjusting interaction with neighbouring cells. This granted the Precursors a limited shapeshifting ability, though most appeared as enormous insect- or crustacean-like beings with chitinous exoskeletons, eight to twelve legs, and four to six eyes.