From the Super Mario Wiki
Skittler Pillars are massive moving structures from Donkey Kong Country Returns and Donkey Kong Country Returns 3D. They are vertical cuboid columns displaying a large carving of a Skittler lowering on a thread. They are wooden, in accordance with the environment's forest aesthetic, and are only encountered during Muncher Marathon as significant impediments.
Skittler Pillars are usually placed apart from one another. Some of them repeatedly ascend and drop down with crushing power, squashing the Kongs if they stand beneath one. They are introduced early in the stage, shortly before the appearance of Munchers, where they cause bananas to fall nearby whenever they hit the ground. If one of these bananas is collected, another will take its place. The spot on which a Skittler Pillar is going to strike is marked by a chipped wooden panel.
The crushing type continues to appear commonly throughout the stage; however, the Kongs will eventually find pairs of Skittler Pillars that face each other, simply rising and lowering simultaneously with a gap between them.
A single hollow Skittler Pillar containing the "N" Letter exists in the level. It acts the same as the other crushing Skittler Pillars, but the Kongs can jump into its hollow space to obtain the letter. Skittler Pillars cannot be destroyed, and even though they are harmless if contacted from the sides, they might briefly close the path ahead of them, delaying the Kongs as they attempt to escape from the swarm of Munchers behind them.