The study looked at diatoms and biogenic silica in the ocean floor to see how well they reflect the environment above. They found that a lot of diatoms and silica are lost as they sink and get buried in the sediment. Only a small percentage of diatoms and silica from deep in the ocean make it to the sediment. Some diatoms are better at surviving this process than others, like Thalassionema nitzschioides. This means that using diatoms and silica from sediments to understand past ocean conditions may not always be accurate, especially in the northern South China Sea.