Stump

Stumps are found in most of the 3D Mario titles with notable appearances being Super Mario 64 and Super Mario Galaxy.

Super Mario 64
In this game, a Stump plays a role in the Behind Chain Chomp's Gate mission. If Mario ground pounds the stump three times, the Chain Chomp is freed and releases the Power Star. They also appear in the Tiny-Huge Island stage.

Super Mario Galaxy and Super Mario Galaxy 2
In the first Galaxy game, stumps appear in Gusty Garden Galaxy and Gold Leaf Galaxy while in the second game, they appear in Puzzle Plank Galaxy, Cloudy Court Galaxy, and Freezy Flake Galaxy. Whenever the stumps are fully "ground-pounded," they will turn red. Stumps have many different actions in these games; making Star Bits and enemies appear are common uses.

Super Mario 3D Land
Stumps rarely appear in this game but when they do, they release coins.