From Destinypedia, the Destiny wiki
Egregore is a strange fungus-like life form that is commonly associated with the Darkness. It is commonly seen on various locations like the Derelict, the Cabal Carrier Glykon Volatus, and the Leviathan.
Egregore is highly similar to many other fungi species on Earth in how they grow and live, but it does not spread its soil but rather between dimensions of space like ethereal conduits, similar to the Ley Lines in the Dreaming City. Most notably, how they feed on death. While Earth fungi feed on dead or decomposing matter, Egregore is drawn to the unique psychological phenomenon that comes from the deaths of sentient beings. The fungus appears to suspend a victim’s mind in the suspension of the death of cognition, akin to falling into a singularity, where it feeds on the victim’s slow death. Ordinarily, it would take centuries for Egregore to spread across a planet or a ship the size of the Leviathan.
Egregore spores are linked to a mycelial network that connects them across the void of space and even alternate dimensions. These spores can apparently "open one's mind" to the Darkness, as well as those consumed by the fungus, and permit affected individuals to pass through energy barriers generated by the fungus.
Via the Crown of Sorrow, Egregore was able to spread through it whenever it is used following its change in use following the experiments aboard the Glykon. This can be seen aboard the aforementioned Cabal ship and, most recently, on the H.E.L.M..
List of appearances