You need oxygen for rust to form in a moist environment. Look for pictures of the Titanic. It also has rust strands with bacteria at their heart. These bacteria use sulfuric acid, sulfurous acid and hydrogen sulfide to dissolve the iron and sort of use it as a food source really an electron donor. A common freshwater bacterium that does this is Thiobacillus ferroxidanse. It’s been 40 years I may have spelled the species name wrong something I never did years ago but if I try to google it I’ll loose everything I’ve typed in and I’m pretty tired an on a cell phone. I’m not sure which species are eating the Titanic.
Here are some samples of a rusty object under the sea, the titanic.
i have megalophobia so i am scared