De Maillet's idea on biology had a similar basis. He thought that life had begun in the water, after the emergence of the highest mountains, but before the continents. He believes that life arose in the shallows surrounding the first land. Sea life, fish, shellfish, algae, diversified and their remains were covered with sediment and became secondary rocks laid down on the sides of primitive mountains. When continents emerged from the water, so did marine organisms. From seaweed developed trees and shrubs, from flying fish came birds. Man's career began as a fish.