Striped doors are found on Aether and Dark Aether in Metroid Prime 2: Echoes. They are identical in construction to all other doors in the game save for their energy shield, which visually consists of slowly expanding hexagonal stripes of black and white (from a distance appearing gray). This shield is vulnerable only to the Annihilator Beam.
Gray doors are quite rare, and are only in the Sanctuary Temple, Phazon Site, Gathering Hall, Catacombs, Aerial Training Site, Temple Security Access, Transit Tunnel South, Hive Controller Access, Sentinel's Path, Hive Temple, and Ing Cache 2 rooms.
Metroid Prime 2: Echoes: The Official Nintendo Player's Guide identifies these as "striped doors" in several instances.
- Metroid Prime 2: Echoes
- "There is a Blast Shield on the door blocking access.
Analysis indicates that the Blast Shield is invulnerable to most weapons.
A mix of light and dark energy may damage it."