Air Stone is a recurring enemy of Mega Man 11, with some variants.
The Air Stone consists on an aerial enemy that shoots eight projectiles in eight directions from their edges, four in the cardinal directions and four at 45 degrees from the cardinal directions. In their passive state, they hide with vibrations, and they cannot be attacked. When the player character goes close to them, they will become completely visible and shoot their respective projectiles. Learning to see them can be useful to know what to do when they become active.
The main Air Stone shoots stones, while the Air Fire shoots small flames that can have the reactions fire has with some objects.