Dark Webbing is named in the Metroid Prime 2: Echoes Bonus Disc and is created by Weblings. The scan in the full game instead describes the Webling. It is only ever encountered twice in-game (all in the same room), so scanning it is a top priority.
Logbook entry
Dark Webbing
Metroid Prime 2: Echoes Bonus Disc
Logbook entry
Obstacle composed of tensile biomaterial, energized by Dark Energy. The Light Beam will be able to disrupt and destroy this obstacle.
Trivia
- When scanning it and viewing its scan model, it will have the same model as its Light counterpart.