Corrosion
Corrosion was a natural process that breaks down metals.

One of the remains at the abandoned Terra Nova colony was a corroded bicycle. ()

The Horta on Janus VI used a natural corrosive agent to dissolve away the metal and nearly disintegrate the automatic machinery, piece by piece, used by the miners on the planet. According to Chief engineer Vanderberg, prior to determining the cause of the corrosion, "There was no reason for it, and our chemists were unable to analyze the corrosive agent." ()

In 2269, Leonard McCoy said that the cosmic cloud creature had the potential to corrode the hull of the . ()

In 2371, corrosive atmospheric specifications created for the Yalosian ambassador who was about to visit Deep Space 9 corroded the carpet in one of the quarters. ()

The schematics of the   found in the Cyrik Ocean were severely corroded. This exacerbated mistakes in Voyager'''s depiction in The Voyager Encounter'', which was inaccurate to begin with due to the Kyrians' warped perception of the ship and her crew. ()

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Chemistry