Glass Tube (object)

The Glass Tube, sometimes referred to as a Power Bomb tunnel or glass bridge, is a recurring object within the Metroid series.
==Description==
Starting with its first appearance in Super Metroid, hallways containing destructible Glass Tubes have become a recurring presence. All types of these glass tunnels or tubes are vulnerable with a Power Bomb. In most cases, planting a Power Bomb directly inside the center of the tube will cause the entire tube to shatter from the large enclosed blast, opening up the pathway allowing Samus to further explore the area outside the tube. In 2D games, these tunnels mainly appear cylindrical. In 3D games, they tend to appear hexagonal.
==Appearances==
===Super Metroid=== 
Main article: Glass Tunnel
A Glass Tube appears within Lower Brinstar, serving as an underwater transport tunnel connecting Brinstar to an elevator to Norfair. The outside of the glass tube is a room submerged in water, which contains a door leading into the water filled Maridia area. Should Samus use a Power Bomb from inside the glass tube, it will shatter, flooding the once water-free area. Samus may then have access to both Maridia and a Save Room underneath the destroyed glass bridge, but will no longer have a straightforward method to cross the doors between Brinstar and Norfair. This requires Samus to also have the Gravity Suit in order to climb to the top of the room and make traversing through this area a breeze. A similar glass tube is discovered within Maridia itself, infested with Sciser in the room. However, it is already destroyed by the time Samus arrives into this room. The tunnel connects to portions of Maridia and houses a hidden exit out of Maridia into the first Glass Tube room.
This is the first appearance of a Glass Tube and is the one of the only glass tubes (if not the only one) mandatory to destroy in order to progress further into the main quest.
===Metroid Prime===
A more metallic tunnel appears within Metroid Prime, making up the center of the room Shore Tunnel within the Magmoor Caverns. This metal bridge bears holographic frames that are vulnerable to a Power Bomb in the center of the bridge and when one is detonated, will shatter the central frames, allowing access to the Lava pool below. Directly underneath this bridge lies a small platform holding the Ice Spreader. Interestingly, the glass frame will always respawn if destroyed when Samus reloads the room. The shape of this bridge is more hexagonal, instead of round.
===Metroid Prime 2: Echoes===
 
Similar to Prime, a long hexagonal Glass Tube is located inside the Hall of Combat Mastery, within the Sanctuary Fortress. Scans label it as a bridge, and unlike previous tubes, this one can be accessed from and destroyed from the outside of the bridge as well if Samus detours around it. Once destroyed, the entire bridge immediately shatters, opening up a pathway between the room itself and the hall leading to the elevator to Agon Wastes.
There is no bridge present within the room's Dark Aetherian counterpart, the Culling Chamber. However, metal bars are still present, indicating the glass bridge was destroyed prior to Samus's arrival, most likely occurring during the Luminoth war.
===Metroid: Zero Mission===
Main article: Ship's large glass tube
In an almost identical manner to Super Metroid, a glass tube appears within the Space Pirate Mother Ship, connecting the ship with the Chozo Ruins, though the left side of the tunnel itself connects to a portion of the Wrecked Ship before the actual ruins itself. Although the map's green color may refer to it as part of the Chozo Ruins, it is likely referring to the ruins area outside the tube. The Pirate forces use this glass docking tube to reach and infest the Chozo Ruins. Samus traverses through this glass tube at least twice during her visit in Chozodia: the first time is as Zero Suit Samus, en route to the Top of the ruins while escaping Zebesian forces. The second time is on her return trip back into the Mother Ship, after she has acquired the Legendary Power Suit. At this time, the Acid Rainstorm has subsided, displaying a clearer sunny weather outside. If Samus obtains the stolen Power Bomb tank from the Mother Ship, optionally she can return to this Glass Tube a third time and shatter it, allowing her to explore the area below the Chozo Ruins, which appears to be portions of the buried Wrecked Ship. This area ultimately leads back into a familiarly explored area of Crateria, allowing Samus to return to previously explored portions of Zebes in order to obtain any missing upgrades or Expansions missed out on pre-Mother Brain battle.
Regardless if the Glass Tube was destroyed or not, it ultimately ends up destroyed along with the Mother Ship itself after Samus successfully defeats Mecha Ridley and escapes the Self-Destruct sequence. It is rumored that this tube may be the same shattered tube seen in Maridia from Super Metroid. 
A hidden game flag relates to this tube, naming the event as GLASSTUBE ( ｶﾞﾗｽｶﾝ ｺﾜﾚ ). When active, the flag leaves the glass tube in its broken state. Interestingly, this flag can toggle the state of the glass tube during the Zero Suit Samus exploration, under the Acid Rainstorm weather, which isn't normally possible even if Power Bombs were hacked to attempt to destroy the glass tube early (it is indestructible at this time by early Power Bombs).
===Metroid Dread===
A glass tube is present within Hanubia, near an elevator.
==Scans (Prime series)==
Metroid Prime
:"Scan shows stress fractures in Bendezium frame."
Metroid Prime 2: Echoes
:"Structural scan complete.Bridge is composed of numerous alloys, including Denzium.Exposure to portal energies has weakened the structure considerably."
==Gallery==
Ship's large glass tube cracking.png|A Gravity Suited Samus cracks the Mother Ship's glass tube.
Shore Tunnel MPR.jpg|Prime's metal and glass frame bridge in Metroid Prime Remastered.