A Data Capsule is a spherical item capable of storing the data of an extracted power that can be implanted into the body of another being. This individual can then use the ability to their advantage.
The Body Snatcher traps Samus Aran in an Ability Disassembly and Conversion Device at the end of Samus and Joey and violently converts her important abilities into data, which he then extracts into six capsules. Although Samus escapes and kills the Snatcher, Greed appears before her and takes the capsules off with him to the Extreme Galaxy. The capsules are given to the henchmen he calls the Deadly Six Stars, who keep the capsules in their bodies and use the abilities from them to wreak havoc on the cosmos.
To recover the Capsules and restore her abilities, Samus is forced to do battle with each Star and find unconventional ways to defeat them. The Varia Suit's Data Capsule is lost in the explosion of the volcano on the ocean world, leaving Samus without one of her signature abilities. Near the end of Metroid EX, Bishop reveals that he secretly recovered the Varia Suit and also possesses the Data Capsule containing the Plasma Beam, which manifest as an impenetrable defense shield and powerful beam that cuts through Knight. After Bishop's death, the Capsules join an unconscious Samus, who stands up, completely restored to full power.