Not much, since the ocean floor tends to be quite young on geological terms. For example, the oldest parts of the floor of the northern Atlantic ocean only star

Not much, since the ocean floor tends to be quite young on geological terms. For example, the oldest parts of the floor of the northern Atlantic ocean only started to form after Laurasia broke apart 50 million years ago, and the floor of the Pacific ocean is regularly recycled in the subduction zones of the pacific ring of fire.