Nitron (ニトロン,Nitoron?) is a flying eye-like enemy in Mega Man 3. They appear in the first section of Gemini Man's stage (the surface of the space glacier), both regular and Doc Robot. When Mega Man is close, it swoops down and drops three fireballs that spout into small flame geysers, a little bit like what Flame Blast does later on in Mega Man 6 and also reminiscent of Heat Man's Atomic Fire from Mega Man 2 (and Doc Heat Man in Mega Man 3).
In the Gemini Man Doc Robot stage, the color of the fire is blue and their body is yellow.