Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020] Domain Bacteria Woese et al. 1990 [paraphyletic?] Phylum Aquificae Reysenbach 2001 [monotypic] Class Aquificaeᵀ Reysenbach 2002 Order Aquificalesᵀ Reysenbach 2002 Family Hydrogenothermaceae Eder and Huber 2003 Genus Sulfurihydrogenibium Takai et al. 2003 Sulfurihydrogenibium kristjanssonii Flores et al. 2008