Lysocline

Imagine you have a cup of water with some dirt at the bottom. The dirt settles down where it's not easy to see or touch. Now, let's imagine a similar situation in the ocean. The dirt in the ocean is not easy to see, but some microscopic organisms settle on it just like the dirt in the cup of water. These organisms consume oxygen to survive, and when they die, they fall to the bottom and consume even more oxygen.

The lysocline is where the water gets so deep that the pressure causes the water to become acidic due to dissolved CO2. This affects the ability of tiny organisms to make their shells, which can cause their bodies to dissolve and become part of the ocean's mud. When you dig into the ocean floor, you can find a layer of mud where this process happens.

Think of the lysocline as the point in the ocean where the pressure and acidity cause the microscopic organisms' remains to stop sinking to the bottom and dissolving. It's like a line where everything below it is getting dissolved, and everything above it stays intact.