- "The Praetorian's distinctive head crest is also a source of Alien Spores."
- ―AVP:E Alien Bestiary
- "Spores coat living organisms and grow upon them for an extended period of time. Spores have numerous sensors, and they relay what they 'see' by encoding this information on ambient radiation that bounces off of them and then finds its way to other aliens. This 'spore sight' enables the hive to track hosts long after they have left the vicinity of any nearby Aliens. Spores defeat Predator cloaking."
- ―AVP:E Praetorian:Spore Emission
Alien spores are a type of alien matter secreted by certain castes of alien. They serve to alert a Xenomorph to the presence of prey, even if that prey is using a Cloak to disrupt the Xenomorph's "vision". This prevents enemies, such as the Spear Master, who could otherwise one-shot-kill them from doing so. Praetorians, Queens, Hive Nodes, and Runners produce such spores.
The Runner in particular, when upgraded, can use it's claws and force a particularly aggressive version of the spores into a prey items body, which not only allow them to be located but cause the blood of the afflicted to become black and soupy, sickening them and causing them to vomit up said blackened body fluids. If that prey item escapes or kills the Runner, other Xenomorphs can find them easily regardless of how far they've travelled.