A vast living sphere some hundred thousand years old which, dying, stopped the USS Discovery in order to hand on everything it had learned in its lifetime.
The Sphere is a single enormous organism of both organic and inorganic matter that wandered the galaxy for about a hundred thousand years, observing and recording all it met.
It appears in the Discovery episode An Obol for Charon. It pulls the ship out of warp and holds it fast, and a flood of signals scrambles the universal translator and cripples systems. Saru, who believes he is dying of the Kelpien condition vahar'ai, recognises that the entity is not attacking. It is near death and wants its memories preserved. Discovery receives the transmission and the Sphere expires in a burst of energy.
The archive shapes the rest of the series. Control tries to seize it to achieve full consciousness, the data defends itself against deletion, and it later merges with the ship's computer to become Zora.