Biodegradable plastics have been proposed as a solution to the problem of plastics littering. However, the polymer industries and consumers have been sharply against the idea of biodegradable plastics because it appeared to conflict with the underlying theme that plastics should be made as stable as possible, and as cheap as possible. The best way to solve these controversies is to create a biodegradable plastic with appropriate stability and price. Before the emergence of human-made plastics (polymer) about 300 years ago, nature produced a variety of biodegradable plastics composed of biological polymers. In this presentation, I will present how biodegradable plastics have been utilized in our ecosystems, and suggest nano-polysaccharides including nanocellulose & nanochitin as a source for biodegradable plastics.