Related by context. Frequent words. (Click for all words.) 63 sedimentary rock 62 diatoms 62 olivine 60 Precambrian 60 archaea 59 fossils 58 Archaea 58 single celled organisms 57 diatom 56 hydrothermal vents 56 single celled 56 microscopic organisms 56 basalts 56 sediments 56 landforms 56 volcanism 55 multicellular 55 rocky planets 55 Carboniferous 55 Late Cretaceous 55 sedimentary rocks 55 cyanobacteria 55 silicates 55 terrestrial planets 55 organisms 54 fossilized remains 54 organic molecules 54 alga 54 iron oxides 54 subduction zones 53 geologic 53 calcite 53 Pliocene 53 microbes 53 megafauna 53 theropods 53 abundances 53 tyrannosaur 53 hematite 53 Cretaceous 53 Ordovician 53 eukaryotes 53 melanosomes 52 sauropods 52 eukaryotic 52 geological formations 52 plesiosaur 52 sediment cores 52 peridotite 52 organic compounds 52 glaciation 52 lake sediments 52 volcanic rock 52 Denisovans 52 lava flows 52 mudstone 52 basalt 51 geologically 51 Saturn rings 51 feldspar 51 meteorites 51 sauropod 51 Homo floresiensis 51 Eocene 51 Geologically 51 rock outcrops 51 plate tectonics 50 hydrothermal 50 sedimentary basins 50 stalagmites 50 Ardipithecus 50 lichens 50 sedimentary 50 Cretaceous Period 50 Tiktaalik 50 fossilized bones 50 naturally occurring 50 fossilized 50 tyrannosaurs 50 fossil 50 ejecta 50 Proterozoic 50 gneiss 50 volcanic islands 50 nitrogen fixation 49 biota 49 Microorganisms 49 hot Jupiters 49 intertidal 49 magmatic 49 Quaternary 49 Neandertals 49 seamounts 49 protozoa 49 Paleozoic 49 carbonaceous 49 volcanic crater 49 super Earths 49 comets 49 limestones 49 globular clusters