The sea erupted. Often the sea and land changed places. The immobility of contours of continents and seas, a dogma in geology, has no basis in fact. And immediately there is the problem of the climate. There were ancient climates that were very different from what they are today. If those corals grew where they were found, certainly the Earth was not travelling with the same elements of rotation and revolution which means not in the same orbit, not with the axis directed in the same position as it is today. If you don't believe it, try to conservate corals on the North Pole.