Protoplasm

The Protoplasm is a creature exclusively featured in the television show Captain N: The Game Master. While it is not from the Metroid franchise, Protoplasm does have some similarities to Metroid larvae. Protoplasm appears in the episode "Metroid Sweet Metroid," in which several other Metroid enemies also appear.

The Protoplasm is found aboard the mobile asteroid base Metroid. Protoplasm is a large creature, approximately twice as tall as Kevin Keene, and its wide girth blocks the hallway that it inhabits. Despite its imposing size, Protoplasm does not move at all and simply sits passively.

An Item Sphere is lobbed at the Protoplasm to freeze the creature with the Ice Beam, followed by Kevin shooting it with Kraid's Missile Gun. This combination of Ice Beam and Missiles defeats the Protoplasm (just like Metroid larvae in the games), shattering the Protoplasm into pieces and allowing Kevin and Duke to continue their journey to Mother Brain's Lair.

Trivia

 * The Protoplasm's name may be derived from the Metroid's bio in the Metroid instruction manual: "This protoplasm in suspended animation was discovered on the planet SR388. It clings onto Samus' body and sucks his energy. It can't be destroyed directly with the normal beam. Freeze it with the ice beam, and then fire 5 missile blasts at it."