Though illustrations of the cell often depict it as a bag full of various organelles and folded membranes, this fundamental unit of life is actually organized upon a highly-structured three-dimensional truss structure known as the cytoskeleton. Until the early 1990s the cytoskeleton had been observed only in the more complex eukaryotic cells. But a series of detailed then emerged indicating that the other two domains of life (bacteria and archaea) also have cytoskeletons. The wikipedia entry gives a good introduction to this subject:  Read more