What is the 'buliding block of all life on earth?

The building block of all life on Earth is the cell. Cells are the fundamental units of structure and function in living organisms, capable of carrying out essential processes such as metabolism, growth, and reproduction. They can exist as single-celled organisms, like bacteria, or as part of multicellular organisms, such as plants and animals. All known life forms are composed of one or more cells, making them the foundational element of biological systems.