Fossil formation is a rare event. The fact that fossils are not being formed today under uniformitarian conditions, clearly suggests that the many fossils that we do find in the sediments must be the result of catastrophic burial such as would result from the biblical global flood.
Whether a plant or animal dies on land or sea, the usual scenario is for the body to be eaten or rotted away. Only rapid burial can preserve and fossilize it. That rarely happens under conditions that exist today.