Banana

From Donkey Kong Wiki

The Banana is the most common item featured in the Donkey Kong series. This fruit appears in every single Donkey Kong Country and Donkey Kong Land title. In these games, collecting one hundred bananas will give a Kong an extra life. It is possible for the Kong Family to collect every single banana that appears in the games. Additionally, bananas often point in the direction of secret areas, hidden items, and the end of a level. A Banana Bunch is worth ten regular bananas.

In Donkey Kong 64, there were five colors of bananas - each color could only be collected by a specific Kong. The bananas come in single, bunches of five, or balloons of ten. Bananas were needed to feed Scoff in order to allow Troff to open the door to the level's boss.