Spore Spawn

Spore Spawn is a miniboss in Super Metroid. Reached from the top of the large pink room in upper Brinstar, it guards the game's first set of Super Missiles. It is voiced by Kenji Yamamoto, one of the sound designers. 

Spore Spawn is a gigantic plant that was genetically engineered by the Space Pirates. When Samus enters the room, spores begin to fill the air and the creature's main body descends from the ceiling to swing back and forth in perpetual figure eights. Its shell is impenetrable to all of Samus' weapons: Spore Spawn can only be damaged when it stops to open its mouth to reveal its glowing core. This opportunity initially appears once every three cycles. When dealt some damage, Spore Spawn turns darker, moves twice as fast, and reveals its core once every six cycles. It takes five Charge Beam shots to reach Spore Spawn's second stage, and an additional three to kill it. With Missiles, the respective numbers are six and four. Neither the Charge Beam nor a large supply of Missiles is needed, as Missiles can be refilled by shooting the falling spores. The spores themselves do little damage individually, and compared to later enemies, even contact with the Spore Spawn itself doesn't do much damage. However, at this point, Samus will usually have very few energy tanks, so even that small amount of damage can be trouble. Damage to Samus from direct contact can be avoided by staying in a corner in Morph Ball mode, though the floating spores can still be troublesome.

It is possible to skip Spore Spawn using the early Super Missiles trick. An amusing consequence is that Spore Spawn can be fought later on, with more powerful weapons such as the Plasma Beam which kills it instantly. If Super Missiles are collected in advance, it is also possible to escape the room and start over again (the only such boss battle in the game).

The dead Spore Spawn head is one of a few objects in the game that will shake when wall jumped onto.

Super Metroid manual
"This creature was genetically engineered by the Space Pirates. Its weak point is its core, which is protected by the plant's hard shell."

Trivia

 * Although Spore Spawn does not appear in Metroid: Zero Mission, the boss battle music for the ensnared Imago Larva is a remix of his battle music. Also, the ensnared beast releases small spores.
 * The Puddle Spore of Metroid Prime and Dark Phlogus of Metroid Prime 2: Echoes greatly resemble Spore Spawn in appearance, despite being completely different in species - the Dark Phlogus and Puddle Spore are both animals, whereas the Spore Spawn is a plant.
 * Additionally, the battle with the first form of the Emperor Ing in Echoes is a reminiscent of Spore Spawn, when the eye opens and Samus must attack the inside.


 * Spore Spawn and Crocomire are the only bosses in Super Metroid that leave behind remains. In Spore Spawn's case, it becomes a dried husk.