Flood spore

Flood Spores are used by the Flood as ways of spreading Flood biomass.

Overview
Flood Spores are crucial in the formation of Flood hives. Spores are also used as methods of suffocating future hosts and clearing the area of uninfected hostiles. It is not known if spores take a specific form or if they are just any type of floating Flood biomass. Spores linger through the air clogging air filtration systems and making it easier to infect hosts. If a spore lands on an area that can support it, it will form a Flood gestation pod. If the area does not have enough biomass to support a Flood gestation pod, the spore will spread over floors and walls until it covers as much as it can. It is possible that if a non-infected host inhales or becomes covered with spores,then the host may be infected or the body will be dissolved into the necessary nutrients for the Flood.

Trivia

 * You can see flood spores in Halo 3 on levels where there is massive flood infection.
 * Kusovai was infected when he inhaled too many flood spores.
 * All the spec-ops elites wear assault helmets in Floodgate, to protect themselves from flood spores.