Room MW is large, and contains six raised tanks toward the front and back, in the floor. The center of the floor indicates that an additional three tanks are present, but they are not seen when Samus explores the room. These tanks end up being destroyed during the coming battle. Along the walls are several smaller rooms with testing equipment inside each, including stasis tanks. These rooms can each be locked from the inside with consoles, which are also capable of opening large blast doors to a breeding cage.
After a Power Bomb is used, the room becomes destroyed, with the doors to each small chamber broken open, and the room is splattered with a substance that may either be the Queen Metroid's blood or amniotic fluid, or both. Parts of the wall are broken, with boards and exposed circuitry now visible.
|“||I've located a survivor in Room MW toward the rear of the Bioweapon Research Center. Whoever it is will be a key witness. Secure the survivor's safety.||„|
When Samus is incapacitated by Adam at the entrance to Sector Zero, he informs her that he had located a survivor in Room MW and asks her to rescue them. Once she arrives in Room MW, the door locks behind Samus. Exploring, she finds the survivor - who turns out to be the real Madeline Bergman - hiding in the rightmost chamber on the back wall, keeping the door locked. She knocks on the door, causing her to wake up and panic. She stumbles back, screaming at Samus to stay away, thinking her to be a Galactic Federation assassin.
|“|| Madeline: No!
Samus: No, you've got it wrong!
Madeline: Stay away! Stay away!
Samus: You have to calm down!
As Samus tries to talk her down, Madeline moves to a console in the chamber and unlocks the large blast doors in the room. Samus proceeds through the blast doors, and discovers hatched Metroid Eggs.
|“||Wait... Metroid eggs?! It can't be!||„|
A Queen Metroid then emerges, and Samus engages it in a battle. Halfway through the fight, the Bottle Ship P.A. Announcer announces that the BOTTLE SHIP is intercepting the orbit of Galactic Federation Headquarters.
|“|| This facility will intercept Galactic Federation orbit in approximately 30 seconds. [repeated twice]
10, 9, 8, 7, 6, 5, 4, 3...
—Bottle Ship P.A. Announcer
|“||WARNING. Emergency brakes engaged. Brace for impact. [repeated twice]||„|
—Bottle Ship P.A. Announcer
Both the Queen and Samus are knocked to their sides. Samus takes the opportunity to attack its exposed ovisac before it regains its footing and begins to charge a fatal energy blast. Samus quickly grapples into its mouth and uses a Power Bomb in its esophagus, destroying the Queen and much of the room. After the blast settles, Madeline emerges from her wrecked room and absconds, forcing Samus to chase her through Room MW and other rooms before finally catching up with her in the control room.
The room is entered from an empty, square room with a staircase.
- The 'MW' in the room's name presumably stands for 'Metroid Warriors', as this was where the Queen Metroid was kept and where most Metroid experiments presumably took place, although the Metroids were kept in Sector Zero.