How do I do Samus' power bomb special move?

This one is going back. On Super Metroid, yes Super Metriod, for the SNES, how do I execute the special move Samus does in the game play preview? It is the last move. She he the power bomb highlighted, rolls into a ball, detonates a power bomb, then all of her health is filled while some of her missiles and power bombs dwindle.