Metroid webs

Metroid webs are a substance found in the Metroid-infested caverns of SR388.

Description
In Metroid II: Return of Samus, Metroid webs are found in the Metroid hives deep in the subterranean tunnels of Phase 4. Unlike bushes, Samus Aran can walk through these webs without being harmed, since it deals no damage to her. However, its thick nature means that it will block her missiles, acting as a barrier that hinders her combat abilities. Because Samus must fight an Alpha Metroid and a Gamma Metroid in caves encrusted with Metroid webs, she must first clear out the webbing by shooting it with her beam weaponry.

Metroid webs do not reappear as an obstacle in the official remake, Metroid: Samus Returns. However, the Metroid nest in Area 8 is caked with thick webbing-like material. This webbing also appears in rooms occupied by Metroids in other areas of SR388; it appears that Metroids warp their environment to resemble their hive.

Nintendo Power issue 37
"Not only will you meet up with more Metroids than ever before, but you'll also experience long, vertical tunnels with poisonous plants, restraining Metroid webs, and very few platforms."

Trivia

 * Metroid webs resemble barnacles, a material encrusting the Big Metroid's room in Tourian. Nintendo Power suggests that the barnacles were secreted by some organism, further suggesting a relationship between the two substances.