In most biology textbooks, there’s a clear separation between the three domains of cellular organisms – Bacteria, Archaea, and Eukaryotes – and viruses. This fault line is also typically accepted as the divider between life and non-life: since viruses rely on host machinery to enact metabolic transformations and to replicate, they are not self-sufficient, and generally not considered living entities.

But several discoveries of giant viruses over the last decade have blurred this distincti