Oil drum

Oil Drums are cylindrical metal drums filled with oil that have the ability to produce Fire creatures or other monsters from themselves. They have appeared throughout the Donkey Kong series as recurring undefeatable obstacles.

Donkey Kong
Oil Drums first appeared in the Donkey Kong arcade game. Here they are found in several levels and are quite harmless, unless a barrel ends up being burned up inside them, then they will produce Fire which can harm Mario.

Donkey Kong Country
Oil Drums later appear in Donkey Kong Country. In this game, Oil Drums have two attack patterns. They either expel flames, which can injure Donkey or Diddy, or they will expel enemies (most commonly Slippas). In the level "Oil Drum Alley" Donkey and Diddy must jump from one floating Oil Drum to the next (while they are not spurting fire of course) in order to reach the level's end. Oil Drums that release enemies have a skull and two bones displayed on it. The ones that release flames have the words "OIL" displayed on them. While any barrel can take out the skull Oil Drums, only TNT Barrels can take out the ones that release fire. There's also an Oil Drum boss named Dumb Drum.

Donkey Kong Land
Oil Drums also appear in the semi-sequel to Donkey Kong Country, Donkey Kong Land. There is no real difference between the Oil Drums of Donkey Kong Country and the ones of Donkey Kong Land.

Donkey Kong Country 2 and Donkey Kong Land 2
In Donkey Kong Country 2: Diddy's Kong Quest and Donkey Kong Land II a tipped over Oil Drum can be seen in the background of Klubba's Kiosk.

DK: Jungle Climber
In DK: Jungle Climber, there are barrels that resemble Oil Drums called Oil Barrels. However instead of being obstacles they are a collectible item.