'Rounder (ラウンダー) is a flying enemy in Mega Man 5, which basically looks like a flying eye. They appear in a group of three at the end of the first Proto Man/Dark Man stage (right before the boss gates). They don't really attack, just circle around Mega Man and interfere with his shots (which could be dangerous since it appears along with the Search Mines that also appear near the end of said stage). They also can crash into Mega Man if he jumps before they begin to circle completely, but cause little damage. They can easily be destroyed with the Mega Buster, but, if ignored for a sufficient amount of time, they eventually fly away.
'Rounder 2 is a pair of larger versions of the 'Rounder. They are the boss for the first Mr. X's stages, at the top of what seems to be the outer wall. They run back and forth on a track while dropping bombs and trying to hit Mega Man. They're vulnerable to the Flame Blast and a charged attack from the Power Adapter, which is able to change their direction.