Caterkiller

Caterkiller is a wall-climbing enemy in Mega Man X3. It shoots out bullets from its spines. It looks more like a cactus than a worm, though. Acid Burst causes them to malfunction and paralyze.

Trivia

 * Coincidentally, there is a Sonic the Hedgehog enemy called "Caterkiller", but unlike the Mega Man X3 one, it does indeed look like a caterpillar.