Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       Astra Plinius - celestial bodies
         Universe
           (Supercluster) Virgo-Hydra-Centaurus Supercluster
             (Supercluster) Virgo Supercluster
               (Cluster) Local Group
                 (Galaxy) Milky Way Galaxy veter.
                   (Spiral arm) Orion Arm
                     (Region) Local Bubble
                       Local Interstellar Cloud
                         (Planetary system) Solar System
                           (Planet-satellite system) Earth System
                             (Planet) Earth veter.
                               "spheres" (Earth)
                                 (Sphere) Lithosphere (Earth) - layer of rock
                                   "strata"
                                     "chronostratigraphic units"
                                       "global chronostratigraphic units"
                                         (Eonothem) Phanerozoic Eonothem (541.0 Ma - present)
                                           (Erathem) †Paleozoic Erathem (541.0 - 251.902 Ma)
                                             (System) †Silurian System (443.8 - 419.2 Ma)
                                               1 (Series) †Llandovery Series (443.8 - 433.4 Ma)
                                               2 (Series) †Wenlock Series (433.4 - 427.4 Ma)
                                               3.1 (Series) †Ludlow Series (427.4 - 423.0 Ma)
                                               3.2 (Series) †Pridoli Series (423.0 - 419.2 Ma)