by Jamie — Viruses are very cre­ative ge­netic en­ti­ties. Their su­per­sonic mu­ta­tion rates (com­pared to ours) have al­lowed them to ex­plore a wide range of pos­si­bil­i­ties in genome struc­ture. Thus, while all cel­lu­lar life has dou­ble-stranded DNA genomes, with op­tions lim­ited to cir­cu­lar or lin­ear chro­mo­somes, viruses are rep­re­sented by just about every type of genome imag­in­able.