What happens if you throw a steel ball into the Mariana Trench
The depth of the Mariana Trench is about 11 kilometers. Let's see what happens if you throw a steel ball there. The ball will sink to the bottom under the influence of gravity. But obviously it will be slower than in air due to water resistance. The ball will reach the bottom in about 12 minutes.
For a person, such a depth, of course, is deadly. Not so much because of the cold (at the bottom of the Mariana Trench it is + 1-4 degrees Celsius), but because of the pressure. The pressure here is 1070 times the atmospheric pressure at sea level. Because of this, even the density of water here is higher than the average in the ocean.
For a ball, pressure is not a hindrance; it will only shrink a little.
What happens to the ball further?
Rust is not dangerous to the ball, since there is a minimum of oxygen. But it won't be able to "live forever" either. Anaerobic bacteria live at depth that feed on steel and do not need oxygen to survive. These are the bacteria that are now consuming the Titanic.
Halomonas titanicae is the name given to bacteria found on the wreck of the Titanic. They oxidize iron, using it for chemical reactions and nutrition. And the metal begins to rust even in the absence of oxygen.
This "rust" that runs down the sides of the Titanic is actually caused by bacteria! The same type of bacteria also exists at the bottom of the Mariana Trench.
Similar iron bacteria exist on the surface. Here, for example, how a stream in Scotland with traces of their activity looks like:
But it was Halomonas titanicae that learned how to survive at great depths.
Scientists are even considering the possibility of using such bacteria to clean the seabed from various debris. Including dangerous depth charges and floating mines, preserved from the Second World War.
However, for a person as a whole, the activity of these bacteria is harmful, as it destroys drilling platforms and other deep-sea structures. Well, the ball, in the end, will be completely eaten. Nothing lasts forever in this world! Even, it would seem, in such lifeless places as the cold and dark Mariana Trench.