Newtron

Fierce lizard-like creatures, Newtrons come in two breeds: the lesser-Spotted Blue Newtron, and the Lesser-Spotted-Oh-Heck-It's-That-One Green Newtron. They're both lesser spotted because they hide on walls, perfectly camouflaged. When someone passes, Blue Newtrons fire a ball-bomb and disappear again, waiting for another victim. They can be found - with difficulty - in the Green Hill Zone.