Wall Cancer

Wall Cancer is a crab-like enemy from Mega Man X3, that moves up and down walls. It attacks by shooting two bouncing energy balls from its claws. If X happens to charge up his X-Buster while a Wall Cancer is present, it will charge up its energy balls to an increased size that inflicts more damage. They also appear in Volt Catfish's and Sigma's stages in Mega Man Xtreme 2. 