Sandworm
From Sonic Retro
Sandworm, called Nal (ナール) in the Japanese Manual, is a caterpillar badnik from Sonic & Knuckles found in the quicksands of Sandopolis Zone. They swim around in the quicksand and jump out of it to attack the player. They are very similar to the Caterkiller, differences being the palette and the behaviour. But just like the Caterkillers, they can only be destroyed by jumping on their noggins.