Koins are Kremlings that have a DK coins as shields. If the a Kong approaches a Koin, he will simply bash them away; if they attempt to jump on him they will simply raise their shields and block the jump. Koins are immune to almost any kind of attack. Even TNT Barrels are useless against them. Fortunately you can defeat a Koin by using a Steel Keg. They have to throw the Steel Keg over him, which will then rebound off a wall (sometimes the Kongs must find another way to defeat Koin using the Steel Keg) and hit Koin in the back, defeating him and giving the Kong a DK Coin as reward. Most of the time, Koins are found near the beginning or the end of a level.