Missile Expansion

A Missile Expansion or Missile Tank is an expansion that allows Samus Aran to increase the capacity of Missiles Samus can fit into her Missile Launcher. They are often hidden at the end of secret passages. Usually the first one is found out in the open, however. Missiles are always either the first or second item Samus acquires, sometimes switching position with the Morph Ball. They are found in every Metroid game.

They vary in appearance depending on the games they feature in. Usually however, they are grey and rocket shaped, with a purple tip and several 'fins' at the base. In Metroid Prime they are of similar shape but are black and orange. In Metroid Prime 2: Echoes, the Luminoth had created their own design of Missile Expansion, that somewhat resembled a grenade with orange markings. However, It was still compatible with Samus' Missile Launcher. The standard design of expansion found in Prime also appeared in Echoes, though was only available through the Galactic Federation base. Corruption featured a scaled down version of Prime's Tank, but contained within a canister.

Logbook entry
Metroid Prime Hunters "Increases the capacity of the ARM CANNON's arsenal by 10 MISSILES."