Millstone

A Millstone is a large round circle with an opening in the middle. Gnawty's can be seen piloting one. Millstones serve as an obstacle that can be found rolling down slopes to stop the Kongs. They made their first appearance in Donkey Kong Country and have appeared in Donkey Kong Land.

In Mario Superstar Baseball, a discarded Millstone can be seen in Donkey Kong Jungle.