The Crystal Coconut as it appears in Kong for a Day.
The Crystal Coconut is the treasure of Kongo Bongo Island guarded by Donkey Kong and Diddy Kong. King K. Rool tries to steal it in almost every episode. It appears in the TV series of DKC and several video games.
Donkey Kong Country TV series
The Crystal Coconut first appeared in the Donkey Kong Country TV series. Its history on the show was that it was stolen from an unknown source by the great-great-grandfather of one of the show's main characters, Kaptain Skurvy. Skurvy's great-great-grandfather hid the Coconut on Kongo Bongo Island, specifically in the eye of the mystical idol Inka Dinka Doo. However, after many years, the coconut pops out of its hiding place and is found by Donkey Kong, who is then proclaimed the future ruler of Kongo Bongo Island. The show's main antagonists King K. Rool and the aforementioned Kaptain Skurvy constantly try to steal the coconut from the Kongs; the former wants to use it to take over Kongo Bongo Island; the latter believes it is his birthright as his ancestor stole the Coconut, and seems to want to use it to "rule the seven seas" as well.
The Coconut's powers in the show range widely. It is known to be able to heal wounds, and occasionally characters can look into it (like a crystal ball) and see whatever they wish to. Occasionally the Coconut projects images on its own, often warning the Kongs when Kaptain Skurvy and his crew are returning to Kong Bongo Island (this may suggest that the coconut possesses some level of intelligence). Cranky Kong seems to be able to use the coconut to teleport (in an astral form) to different places, though he must always return to where the Coconut is, even if it has been removed. For the duration of the show, the Crystal Coconut is kept in Cranky Kong's Cabin, inside a globe.
Donkey Kong 64
A Crystal Coconut from Donkey Kong 64.
In Donkey Kong 64, Crystal Coconuts were the power sources for the Kong's special ability. They are semi-common items that are found in most levels.
DK: King of Swing
In DK: King of Swing, Crystal Coconuts were most commonly found in Bonus Stages. Collecting all of them would unlock Wrinkly Kong in the Jungle Jam mode.
Donkey Kong Barrel Blast
Crystal Coconuts appear as items in the game. They are found in red balloons. They grant the player invincibility and the power to perform unlimited Wild Moves.