Phantoon

Phantoon is a Super Metroid boss found in the Wrecked Ship. It is a supernatural ghost entity that is intangible and invulnerable except for its single eye. It is this eye that, when open, serves as its connection to the material world and can be damaged.

Over 4 meters tall, Phantoon resembles a giant squid with a single eye and a large toothy mouth.

The manual implies that Phantoon is the ghost of the Wrecked Ship itself, and states that it is "tapping into Mother Brain's vicious brainwaves." It is possible that Phantoon is controlled to an extent by Mother Brain. The fact that Phantoon is depicted alongside Kraid, Ridley, and Draygon as statues at the entrance to Tourian, may indicate that it is directly affiliated with the Pirates, perhaps being a high-ranked member. After its defeat, the Wrecked Ship gains electric power, and Coverns stop appearing. Strangely, Phantoon seems to share a lot of physical traits with the Powamps from Maridia.

Super Metroid's official guide states that Phantoon is drawing power from the ship's "energy crystals". It supports this statement by noting that the Work Robots, which run on internal power, have also shut down "as a result of Phantoon's gluttony".

Super Metroid Manual
THE WRECKED SHIP HAS BEEN SHUT DOWN BY THE FLOATING GHOST, PHANTOON.

PHANTOON (The Boss of the Wrecked Ship) "The ghost of the ship taps in to the vicious brianwaves of the Mother Brain and attacks adventurers with deadly plasma."

The Battle
Shortly after Samus enters his room, Phantoon will appear in an intangible ghost form, with a semi-transparent quality to its appearance. While in this semi-transparent form, Phantoon will be completely invulnerable to attack. This form is only engaged while its eye is closed.

As its only basic attack, Phantoon will shed blue-hot "tears" of fire from its closed eye. These lightly bounce from the floor and walls, and can be destroyed for energy and ammunition. Phantoon demonstrates the ability to manipulate these tears in many ways, including the ability to link large numbers of these into nearly inescapable chains of fireballs.

To damage Phantoon, it is necessary to strike it while its eye is opened. Once opened, the body will become solid and visibly opaque. To slow Samus's attack, a large ring of fireballs will form around Phantoon's vulnerable body. If Phantoon is not struck within a very short timeframe once its eye opens, it will disappear for a moment and begin shedding blue tears while it is invisible; it will appear once again rather abruptly, with its eye still vulnerable to attack. Using different weapons to damage Phantoon can cause varying forms of reacting behavior. Using Missiles or the Charge Beam with the Ice Beam enabled will cause Phantoon to disappear, and begin to shed blue tears while invisible. He reappears after a few seconds. Using Super Missiles is effective, but this will cause Phantoon to launch long curved chains of fireballs which are extremely difficult to dodge. To dodge them, Samus can either move in Morph Ball to one side after the first fireball swing passes, then to the left and vice versa. Samus can also use the jump combo with her Charge Beam. If Samus uses the Charge Beam without the Ice Beam enabled Phantoon does not disappear, but he continues to move erratically around the room as if his eye is closed. Several charged shots can hit him, making this the safest and most effective method for causing damage. Eerily, Phantoon will keep his eye centered on Samus as he moves. Throughout the battle, Phantoon's coloring will gradually change from a dark green to a very hot red-orange, according to how much damage has been inflicted. Once defeated, Phantoon will center its eye upon Samus, begin to self destruct, and then violently dissipate into the air. This will power the Wrecked Ship, and allow Samus to explore it in more depth.