Miracle Matter is the boss of Ripple Star in Kirby 64: The Crystal Shards. It is the final boss of the game if Kirby does not have all 72 of the Crystal Shards. After defeating it, it will explode, revealing a final, large Crystal Shard. Upon obtaining every Shard, the final world, Dark Star, becomes accessible.
Throughout the course of the battle, Miracle Matter's surface will change to represent one of the game's Copy Abilities. During this time, Miracle Matter will use attacks based on those abilities to harm Kirby. Miracle Matter can only be harmed by whatever ability or projectile is matching the form it is currently in. Otherwise, a force field blocks the attack. For example, if Kirby tries to use Stone while Miracle Matter is in its Cutter form, it does no damage to the boss. As Miracle Matter takes damage, it will stop using some of its forms. Most of Miracle Matter's attacks can be avoided by simply standing in a corner.