An Energy Capsule is an item in the Metroid series that replenishes the energy of Samus'Power Suit. They appear as floating orbs and can be collected by touching them. Energy Capsules are released by killed enemies and the various storage containers of the game worlds.
The amount of energy restored on collecting one depends on its type, which is usually indicated by its color or size; and in different games, different colors restore different amounts, as follows:
Metroid: White, with a flashing red and blue ring around it. Can replenish 5 or 20 energy.
Metroid 2: Small or large, replenishing 5 and 20 units of energy respectively.
Super Metroid: Purple, in either a small or large size, replenishing 5 and 20 units of energy respectively.
In the Super Metroid manga, the strips She Finds a Small O and She Finds a Big O feature Samus killing a Geemer, with an Energy Capsule being left behind. Samus admires its roundness before trying to touch it, however, it disappears.