Crawlton, called Zakin (ザキーン) in the Japanese manual, is a Badnik from the 16-bit version of Sonic the Hedgehog 2 found in Mystic Cave Zone. It is a long blue centipede-like creature that springs out of platforms and ceilings to attack you when you get close. It is possible to see them inside their platform if you keep an eye out. The only way to destroy them is by hitting the head.
They make a return in both versions of Sonic Lost World, featured in Desert Ruins, Tropical Coast and Frozen Factory. In the Wii U/PC version, they serve as normal enemies who will burrow across the ground with their heads above the surface, then lunge out in a swift motion to attack with a noticeably longer attack range than in Sonic 2. In the Nintendo 3DS version, they are larger enemies that can take multiple hits to defeat and are required to be destroyed in order to progress through a Zone. They attack by hiding in a shadow in the ground, then pop out to attack before repeating the pattern. To defeat them, the player must use the Somersault Kick to stun it, then attack the glowing weak spot with a Homing Attack (or less with a charged Homing Attack). When on their last hit, they will swing their bodies around.
It shares some similarity with the Caterkiller from Sonic 1, though isn't quite as dangerous as its 'cousin'.