Dark spore

CAUTION: SPOILERS
Dark Spores are small spheres which ironically seem to be made of pure white light. They have a corrupting influence on creatures that spend too much time exposed to them. They aren't native to the planet of the Pikmin, and much about them remains unclear. The energy that they contain within themselves can only be harnessed by the Complex Parasite. Dark Spores are uncommon and there is one on the final floor of every one of the Dark Caves.

Trivia
The Smoky Progg is created when a Mitite burrows into a Dark Spore. This causes great changes to occur within the Dark Spore, making it no longer a Dark Spore but the creature's nucleus. The Omega Progg, however, is a completely different story.

Portal- Kombat

The unexpected return
In Pikmin: Global Breakdown, Venom Parasite was ordered to find a Dark Spore. When it did, It's mental and physical abilities skyrocketed. It was thought that only Complex Parasite could wield the mysterious Dark Spore's power, but so could Venom Parasite. Using it's newfound skills, the Venom Parasite zombified a tick-like creature. The tick then drained the Pikmin Planet's life resources away. Venom Parasite sapped the planet's entire power with the help of the tick.