Hivemind is a Collective Soul

• Valedor:

"Individually, the minds of the tyranids were nothing, animal spirits. But as a rope is twisted from many strands, and a cable twisted from many ropes, so the hive mind of the Dragon was made."

• Devestation of Baal:

"It is not as it appears, a host of creatures linked psychically, it can instead be seen as a single, massive ­psychic presence: a single mind. These monsters that attack us generate it, they make it as a man makes his soul, but whereas ours are individual, theirs is singular, a single predator, not many."

• Devestation of Baal:

"The tyranids are utterly alien. But we know the hive mind is real. This intelligence is emergent, coming from the billions of creatures in the swarms, but it is not an empty intellect, it is aware. It has a soul.’ ‘You say then this being is a warp entity, born of the immaterium?’ asked a Librarian. ‘In our librarius we have theorised it is but another thing of Chaos wearing xenos skin.’ ‘Codicier Laertamos, Brothers of the Red,’ the herald skull announced. Scaraban shook his head. ‘I am sure its origins are in this realm of being. We are not alone in holding this opinion of its nature. The reports of Inquisitor Kryptmann, others in the Inquisition and the Magos Biologis suggest so, at least those that support this interpretation. Perhaps what we are seeing is a creature part-way to spiritual transcendence, a gestalt made of the minds of billions of brute animals trapped half in and half out of the warp by unending hunger?"