SR388

SR388 is a planet that was visited by Samus Aran during Metroid II: Return of Samus and then later on in the very beginning of Metroid Fusion (the rest of the game takes place on the Biologic Space Laboratories research station, which orbited the planet at the time of the game.) An asteroid belt is shown to be in close proximity. The place where Samus finds the Baby on the planet is also shown in flashback in Metroid: Other M.

Complete Map of SR388 :

Geography
The barren surface of SR388 was notable for its rough, rocky and dry terrain. Underneath SR388's surface was a vast maze of tunnels and "dangerous liquid". Since the planet was once inhabited by the Chozo, it is safe to assume that they created much of the underground complex.

The entire game of Metroid II: Return of Samus took place on SR388. The planet consisted of rough and rocky terrain and ruins of the ancient Chozo civilization. The Chozo had since abandoned SR388 and most of their colonies were still there, although many had deteriorated into ruins. Also, many robots and drones left by the Chozo were still functioning during Samus's mission on the planet; it is unknown what their original purposes were, but these aggressive synthetic beings have seemingly gone rogue since then.

Acid on SR388 blocked off many of the underground caverns and ruins of the planet. There were also frequent earthquakes that occurred and when they did, it usually happened in conjunction with the liquid level decreasing, often-times exposing new caverns or even ruins of the Chozo civilization to be explored.

Biologic Space Laboratories Research Station
The Biologic Space Laboratories research station was a space station created out of an asteroid that orbited SR388 in Metroid Fusion. It was created by the Galactic Federation and was the main facility where native creatures to SR388, along with other organisms from various planets, were brought in and studied. The Galactic Federation took a special interest in the planet after the discovery of Metroids. After Samus had been assigned to eradicate the Metroid species, the Galactic Federation went back to SR388 to collect more samples which would lead them to the discovery of the X Parasite. Eventually, this new find brought them to the station and Samus was forced to change the Biologic Space Laboratories research station's orbit so that it impacted the planet in hopes of not only destroying the X on the station, but also on SR388.

The BSL's Sector 1(SRX), created to be a perfect replica of SR388's environment, was secretly used by the Galactic Federation to raise Metroids through their natural life-cycle; these specimens were created using the DNA of the only surviving Metroid from the species' extermination on SR388 caused by Samus Aran.

Metroid Fusion
The events of Metroid Fusion take place mainly on the Biologic Space Laboratories research station orbiting the planet. The introduction involves landing on the planet for a research mission and Samus contracting the X Parasite. At the end of the game, Samus evacuates the X infested station and crashes the complex into SR388; subsequently making the entire planet uninhabitable and assuring the extinction of the X Parasites.

Interview
"In the "Metroid" manga, it describes that "The Chozo developed the Metroids in order to exterminate the X living on SR-388", but I think it was previously established that "there is a high probability that the Metroid destroyed the civilization on SR-388." I think it was the X that really destroyed SR-388."

Yoshio Sakamoto: "I think SR-388's civilization was destroyed and the Chozo left for Zebes after the Metroids were released into the wild (became feral). The Galactic Federation, not knowing the reason why the Metroids were developed, requested Samus to clean them up ("Metroid II"). The result of Samus exterminating the Metroids was that the propagation of the X could permit the SR-388 ecosystem to be destroyed ("Metroid Fusion")." 

Creatures
There were a variety of creatures on SR388, the most well-known being Metroids. There were also several mechanical creatures the Chozo left behind still known to have functioned.
 * Alpha Metroid
 * Arachnus
 * Autoad
 * Autom
 * Autrack
 * Blob Thrower
 * Chute Leech
 * Drivel
 * Flitt
 * Gamma Metroid
 * Gawron
 * Glow Fly
 * Gravitt
 * Gullugg
 * Gunzoo
 * Halzyn
 * Hornoad
 * Meboid
 * Metroid
 * Queen Metroid
 * Moheek
 * Moto
 * Mumbo
 * Needler
 * Octroll
 * Omega Metroid
 * Pincher Fly
 * Proboscum
 * Ramulken
 * Seerook
 * Septogg
 * Senjoo
 * Shirk
 * Skorp
 * Skreek
 * TPO
 * Tusurmi
 * Wallfire
 * Yumbo
 * Yumee
 * X Parasite
 * Zeta Metroid
 * ULF 2

Areas
''Note: Each area is named in most official walkthroughs of the game, such as in Nintendo Power. They are not named ingame.''

Phase 1
Phase 1 is the surface area of SR388, where Samus' Gunship lands, and the first Alpha Metroid is fought.

Phase 2
Phase 2 contains 4 Alpha Metroids.

Phase 3
Phase 3 contains 6 Alpha Metroids, 2 Gamma Metroids and the optional miniboss Arachnus.

Phase 4
Phase 4 contains 1 Alpha Metroid and 8 Gamma Metroids.

Phase 5
Phase 5 contains 1 Gamma Metroid.

Phase 6
Phase 6 contains 1 Alpha Metroid and 1 Gamma Metroid.

Phase 7
Phase 7 contains 4 Alpha Metroids and the only 3 Zeta Metroids in the game.

Phase 8
Phase 8 contains 1 Alpha Metroid and 4 Omega Metroids.

Phase 9
Phase 9 is the final area of SR388, containing the Queen Metroid itself, 8 normal Metroids, and the Baby, which Samus brings back to Ceres Space Colony.

Trivia

 * SR388 is the last of four planets to be destroyed, even if not her intention, by Samus Aran, the others being Dark Aether, Phaaze and Zebes.
 * As mentioned before, artificial beings seemingly created by the Chozo can be found among the latter's ruins on SR388, many of which have weapons installed on them and attack on sight. It is possible the Chozo created them to keep the native wildlife at bay or more specifically, to use against the dangerous X Parasites.


 * Ever since the discovery of the Metroids and Chozo ruins on SR388, it was believed that the life-sucking organisms were responsible for the supposed annihilation of the Chozo inhabitants of the planet. However, with the existence of the X Parasite uncovered, the initial theory has been put into doubt, with the X now being the possible main culprit.
 * During the game Metroid 2, SR388 seemed to have a relatively low population of wildlife. The X Parasites were seemingly responsible for this, as stated by Yoshio Sakamoto and the Metroid manga. This would also explain why, in Metroid Fusion, the BSL Station's SRX (a sector that perfectly replicates the planet) contained very few of SR388's wildlife seen in the earlier game; after the extinction of Metroids, the X undoubtedly resurfaced in large numbers and steadily reduced the flora on the planet even further (if not completely), making Galactic Federation Researchers' task of collecting varied specimens a difficult one.


 * Metroids may have also contributed to the near extinction of the bioforms inhabiting SR388, given their vicious nature.


 * The planet's name is pronounced differently between games. Fusion renders the last two numbers as an "88" (eighty-eight) while Other M makes them distinct digits as "8-8" (eight-eight).

Links

 * Manga: Chozo's X Parasite discovery
 * Manga: Federation's Metroid discovery