SPEROs  (pronounced as 'spare-oh', or sparrow) are probes sent by the Koppaites to search for a planet with edible sustenance on it in order to save their planet Koppai, as seen in the opening sequence of Pikmin 3. SPERO 3 is the last one searching and is the one that finds PNF-404, a planet with bountiful food to sustain Koppai's population.
SPEROs are used as a storage device for the fruit collected in Pikmin 3's Mission Mode, comparable to the Ship's Research Pod in underground areas in Pikmin 2. They appear in every stage of Collect Treasure mode and a few stages of Defeat Enemies mode.
In Mission Mode, SPEROs are used to:
- Collect fruit and enemies (Collect Treasure mode only)
- Collect berries from Burgeoning Spiderworts and creates an Ultra-Spicy Spray.
- Revive Louie after he is rescued (Only appears in the last 5 stages)
- SPERO also means "I hope" in italian. Given the probe's mission, it seems fitting.
- As SPERO is written in all caps, it probably is an acronym, but what SPERO stands for is never mentioned in the game.