Started out as plankton tiny plants and animals millions of years ago?

Plankton, which includes both tiny plants (phytoplankton) and animals (zooplankton), form the foundation of aquatic food webs and have existed for millions of years. These microscopic organisms are essential for the Earth's ecosystems, contributing to oxygen production and serving as a primary food source for larger marine life. Over geological time, some planktonic organisms evolved into more complex life forms, influencing the development of marine biodiversity. Their ancient presence highlights the crucial role they play in maintaining the health of oceanic environments.