Backtracking After Area 8

Walkthrough: Before heading back to your gunship after defeating Queen Metroid and finishing the game, make sure you head back to previous areas to finish collecting the all the collectibles. This way, you will earn 100% Completion for each area, thus earning yourself all of the Chozo Seals.

Missile Expansion (Area 7): In the first room of Area 7 has more blue crystals. Let Baby Metroid take care of those so you can Bomb the weak spot on the path to find this Expansion.

Missile Expansion (Area 8): Go back to the first Teleportation Statue in Area 8. Shoot a Missile as the weak spot nearby, and then let Baby Metroid remove the crystals so you can reach the next room with this Expansion inside.

Missile Expansion (Area 8): Just before the main room of Area 8, there will be more crystals that Baby Metroid can help with so you can reach this Expansion.

Super Missile Expansion (Area 1): Head to the room where you obtained the Ice Beam. Bomb the weak point in the floor to find an area with more blue crystals. Let Baby Metroid destroy them, and then shoot a Missile at the left wall to find this Expansion.

Super Missile Expansion (Area 2): In the tall room on the left side of Area 2, let Baby Metroid destroy the blue crystals in the lower section. From there, use the Spider Ball on the ceiling to make it over the breakable floors, Bombing the wall to find this Expansion.

Super Missile Expansion (Area 2): Go back to the tall and long passageway in Area 2 that you once had to use your Screw Attack, and break through the weak spot again. There should be another weak block inside the new section you find, which is where this Expansion is found.

Super Missile Expansion (Area 4): Head back to the Aeion Recharge Station where you were once chased by the mechanical beast. Go to the right to find a door blocked by a wall. Roll through the top, and then let Baby Metroid destroy the crystals you come to. Go back to the previous room and use your Plasma Beam to shoot through the wall and open the door. Roll back over the door and enter before it shuts, grabbing this Expansion after you do.

Super Missile Expansion (Area 6): Head to the right side of Area 6, letting Baby Metroid remove the crystals as you use your Grapple Beam to pull on the red orb you'll find. From there, Bomb the weak spot below you and roll through. let Baby Metroid clear the next set of crystals so you can reach the Expansion.

Super Missile Expansion (Area 8): Around the poisonous flora you passed just a little earlier are some blue crystals. Let Baby Metroid take care of them so you can finally make it to the Expansion.

Aeion Tank (Area 1): To the right of the lava room yet still to the left of the Save Station is a passageway with a room underneath. Stand in the passageway and use your Plasma Beam on the green substance on the door just on the other side of the floor. Get inside, and then let Baby Metroid destroy the blue crystals you come to. Shoot a Missile at the weak spot on the wall, and then run through to reach the Tank.

Aeion Tank (Area 4): Head to the left side of Area 4. You should have passed this Aeion Tank earlier, but you couldn't reach it because of the blue crystals. Let Baby Metroid take care of them so you can finally reach this Tank.

Power Bomb Tank (Surface Area): On the right side of the Surface Area, drop down a few floors and let Baby Metroid destroy the blue crystals in your way. This will allow you to reach a room with the Tank inside.

Power Bomb Tank (Area 2): Head through the small passageway near the Elevator that takes you to Area 3. Let Baby Metroid remove the blue crystals you come to so you can find this Tank.

Power Bomb Tank (Area 3): Just above the Teleportation Statue is a hallway on the left, the same that contains a maze. Let Baby Metroid remove the blue crystals, and then Spider Ball to go over the breakable floors to reach this Tank.

Power Bomb Tank (Area 3): In the center of Area 3 is a door blocked by a yellow barrier. Use your Power Bomb to open it, and then inside to find this Tank. As simple as that!

Power Bomb Tank (Area 5): Head down just past the Chozo Seal. Have Baby Metroid remove the crystals to the right, and then Bomb the weak spot to find this Tank.

Power Bomb Tank (Area 5): Head to the passageway between the two elevators on the lower portion of Area 5. Enter it from the right side so Baby Metroid can remove the crystals so you can find this Tank.