The basis of all life on Earth is the cell. All creatures on Earth are made of cells. I am not going to dwell on the biology of cells and much it is not that relevant. But I do want to point out a few things. First of all, there are 2 sorts of cells. As we think all the prokaryotic cell, which is fairly simple and it is the thing that all bacteria are made of. And then we have a eukaryotic cell, much more complicated beasts on the right, which did not appear until well into the history of the biosphere on earth. And there are many single-celled eukaryotes. But there are also and importantly multicellular organisms and all of those are based on the eukaryotic cell.