Metroid/Items

Energy and Missiles
Throughout the game, some enemies will leave items behind after you destroy them. Until Samus collects her first Missile Pack, the item will always be energy. Most energy orbs provide 5 units of energy. Occasionally, stronger enemies will leave orbs that provide 20 units of energy. After Samus has obtained missiles, enemies may drop missile ammunition as well. Each flashing missile that Samus picks up adds two missiles to her supply, up to her current maximum capacity. The current amount of energy and missiles in Samus' possession is always shown in the upper-left corner of the screen. Energy is shown by a number ranging from 0 to 99, with squares accumulated for every Energy Tank that Samus collects. A full blue square represents another 100 units of energy which will empty out if the current energy tank is depleted. Missiles are shown ranging from 0 to the maximum capacity of 255.

Power-Ups
All items besides Missile Packs and Energy Tanks are closely guarded by Chozo statues. They are contained in energy orbs that only Samus' beam weapon can disrupt in order to claim their contents. These statues are typically hidden behind red doors that need to be opened with rockets, so make sure you have a good supply of them before you seek out power-ups.