Rock

Rocks are throwable items from the game DK: King of Swing. These projectiles are found near Pegs or Peg Boards and can be picked up by Donkey Kong using or. If Donkey Kong is holding a rock and swings on a Peg with the opposite hand, he is given the ability to launch the rock. It can be used to break open barrels to reveal secrets or other items. Rocks can also be thrown at enemies in order to defeat them. They first appear as items in the opening area of Necky's Canyon in the Wild West World. They reappear in the same world during the boss battle against Fire Necky. Fire Necky spits fireballs, which shortly crystallize into rocks, in the direction of Donkey Kong. These rocks are the only way to defeat Fire Necky. In the level Ice Castle, Kremlings have the ability to throw rocks at Donkey Kong, as well.

In-game description
Instruction Booklet
 * "To throw a rock, grab it with the or  Buttons and then release it. Rocks can be used to kill enemies and smash open barrels."