 A clarification necessary at the outset is that none of this work depends on or justifies drawing a hard line between microbes and non-microbes. Life is not most effectively divided into two obvious groups of microbes and macrobes, nor unicellular and multicellular organisms (see  Table 1).  These are terms of pure convenience, with many exceptions (O’Malley 2014). Older “kingdom” perspectives identified at least two kinds of microorganisms (bacteria and protists), plus three kinds of multicellular organisms (plants, fungi, and animals) (Whittaker 1969). Subsequent classifications expanded the category to which bacteria belong, and sometimes continued to conflate them with a superficially similar group of organisms now called Archaea (e.g., Margulis 1996). From cell-biological and evolutionary perspectives, however, lumping Bacteria and Archaea together as one kind of life is seriously misleading (Woese 1994; Pace 2006; Embley &amp; Williams 2015;  Table 1).