Stones

Because this subject has no official name, the name "Stones" is conjectural.

The President near a pile of rubble.

Rubble is found in small piles in Pikmin, and its use is exactly the same as that of the Nectar Weed. Pikmin collect pools of Nectar from it when they pass over an area of the stuff, whether directed to by the Captain in charge or not.

As with the Nectar Weed, Rubble is found in every area in the first game, and only in overworld locations such as the Perplexing Pool and Wistful Wild in Pikmin 2.