When Robert Ballard’s team of explorers discovered the Titanic on the Atlantic floor in 1985, no one was surprised that it was covered with rust. But 10 years later, when the Titanic’s gymnasium roof was discovered collapsed, researchers got a lot more curious about the corrosive material on the ship.
Was something other than rust at work?
A closer inspection showed the “rust” was actually red/brown stalactites, which were nicknamed “rusticles.” The rusticle structures contain both rust and complex communities of bacteria that live off the rusting metal. (The same iron related bacteria plug up pipes, screens, and pumps in water wells.)
How do we know that? Look at this PDF. In expeditions in 1996 and 1998, microbiologist Roy Cullimore was brought on board to analyze the rusticles and see if the bacteria were playing a role in the ship’s destruction. He used a simple experiment to do this.
Cullimore took unexposed slide film and developed it. He put the black slides into bags made of Aida cloth, which has small holes in it that allow bacteria to pass through. If bacteria were present on the ship, they would eat the emulsion side of the slide film inside the bags, releasing colors in the emulsion and staining the Aida cloth. Under a microscope, the colors would reveal complex patterns of bacterial activity.
That’s exactly what Cullimore found. He took samples of rusticles to his lab for further study, which has shown that there are a variety of microbes present in them. They’re contributing to Titanic’s deterioration, and will eventually help cause its collapse. Scientific estimates about how long Titanic has left range from 15 to 450 years, but at some point in the future the mighty ship will be nothing more than an iron deposit on the ocean floor.
You can do an experiment at home similar to Dr. Cullimore’s. You’ll need:
Now follow these steps.