Baku Bakus are creature with a spherical body and no limbs. They are covered in white fur with round brown spots and have a large jaw with a green inside. Additionally, their eyes are shaped like black crosses.
Baku Bakus are only encountered in Hidden WorldZone 4. These creatures appear inside bubbles that either remain in stationary positions or move around in linear patterns. While inside their bubbles, the Baku Bakus are constantly chomping. When the player lands on a bubble with a Baku Baku and leaps to another, the creature gets released and starts to slowly follow Sonic. Larger bubbles can contain five Baku Bakus at once, but they release the creatures in the same way. Some of these larger bubbles are surrounded by green slime bumpers that can deflect Sonic or Iron Balls.
Baku Bakus cannot be attacked directly. Instead, the player must use the local bubbled Iron Balls. When leaping off Iron Ball bubbles, their Iron Balls will be sent flying in the opposite direction of the player. By aiming correctly, the player can launch the Iron Ball into the Baku Baku. One hit from an Iron Ball will destroy a Baku Baku. Also, if the player gets out of the Baku Bakus' line of sight, the creatures will turn around and move in the opposite direction.
A giant Baku Baku with white teeth appears at the mid-point of Hidden WorldZone 4. This large creature functions as unusual mini-boss and it is mandatory to defeat it to clear the Zone. The creature comes in slowly from the left side of the screen and starts moving forward while chomping at a slow rate. Its large body pops all bubble around it and reflects Iron Balls.
When facing it, the player has to escape the giant Baku Baku while trying to fire Iron Ball into its mouth when it opens it. Every time the giant Baku Baku swallows an Iron Ball, it splits out a huge amount of Animals. It then starts charge rapidly forward. After getting hit twice, the creature will summon a green slime shield around it with holes in it. This shield will bounce back Iron Balls, so deploy the Iron Ball when the holes in the slime shield and the giant Baku Baku's mouth align. Upon receiving this hit, the creature will be defeated and the player will have cleared the Zone.
Like many new enemies in Sonic Lost World, all variations of the Baku Bakus has not been listen in any official source. Instead, they are referred to as "baku baku" in the game's source code.
Baku Bakus bear an uncanny resemblance to the Pac-Man, the mascot of the Japanese video game company Namco. More specifically, they resemble the character's original 8-bit sprite from the first arcade game in 1980.