At the beginning of history, when there was no life on earth, microscopic algae modified the atmosphere of our planet by producing oxygen, thus building the path for the evolution of life. Later, algae landed on earth and gave rise to the plants that grow around us today.
This is how algae occupy the first link in the food chain as the origin of the plant world on Earth.

Today, four billion years later, algae are once again an alternative to face the dangers of global warming and the unprecedented food challenge.