Bead Worm

The Gigapolis Zone Boss (referred to as Dangerous Ball Tower (デンジャラス・ボールタワー) in the Japanese manual and Bead Worm in the US manual) rises up in the beginning, sways back and forth, launches its segments at you, and then replaces them to begin the cycle anew. Luckily, the head’s top is weak, and so you can destroy the tower in just three hits by jumping at it and landing squarely on the top of its head. It'll throw its bottom-most body segment in the air, so stay on the ground. Repeat this process two more times to defeat the boss.