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 Thermotogae Reysenbach 2001 [monotypic] Class Thermotogaeᵀ Reysenbach 2002 [monotypic] Order Thermotogalesᵀ Reysenbach 2002 [monotypic] Family Thermotogaceaeᵀ Reysenbach 2002 Genus Fervidobacterium Patel et al. 1985 Fervidobacterium islandicum Huber et al. 1991