There are several biological entities for which it is an open question as to whether they are alive. Viruses, for example, are units of genetic material encased in a protein coat. It is unknown whether all viruses share common ancestor (Koonin et al. 2006, Moreira and López Garcia 2009) nor how they originated, be it escaped transposable elements, reduced cells, or some ancestral third option (Forterre 2006b). The status of viruses as living is mired with controversy, with some people holding virons to be alive, others believing them not to be, and a third camp has them as living only in the context of an infected cell, but a mere ‘seed’ otherwise (Forterre 2010).