Spore Meteors are large creep filled sacks that fall from the skies. They occur across all campaigns, but are rare. They tend to fall in groups of five, exploding and crushing players on impact. Each spore will spread a small patch of creep when it lands similar to the creep spread by a dead Infestor. In extremely rare occurrences, a Spore Meteor will serve as a drop pod and contain a Brain Bug or Brood Mother.
Erebos (Form One) is the most common culprit of Spore Meteors. When players first encounter Erebos, he will constantly summon waves of Meteors from the skies. The only way to stop this is to injure him sufficiently that he retreats. Erebos's Meteors are far more dangerous on higher difficulties. On Recruit they will simply explode, but on higher difficulties they inflict greater damage and leave behind a patch of creep.
On Survival Mode, special Spore Meteors will fall on rounds 10 and 20, and then they will fall every 4 rounds after that. These Meteors will not hurt when they explode, but they will spread a special creep that can not be killed. This is nicknamed perma-creep by most players. The standard Meteors will also fall randomly.