Related by context. Frequent words. (Click for all words.) 56 hydrothermal vent 49 planktonic 48 hydrothermal vents 48 volcanic vents 48 Cyanobacteria 47 Lake Vostok 46 foraminifera 46 underwater caves 46 lava tubes 46 microscopic organisms 46 single celled 46 tidal pools 45 magmas 45 marine sediments 45 lava tube 45 Valles Marineris 45 magma chamber 45 alga 44 microscopic algae 44 icecaps 44 primordial ooze 44 Weddell Sea 44 icy crust 44 seamount 43 biosphere 43 oceans 43 deep 43 lithosphere 43 Arctic permafrost 43 microfossils 43 biogeochemical 43 volcanic crater 43 Namib Desert 43 diatom 43 salt crystals 43 protozoan 43 Oort Cloud 43 cenotes 42 anoxic 42 sea creatures 42 limestone cave 42 extremophiles 42 stalactite 42 diatoms 42 fissures 42 oceanic crust 42 lavas 42 fissure 41 craters 41 abiotic 41 stromatolites 41 lunar soil 41 ocean 41 continental crust 41 basalts 41 permafrost 41 moon Europa 41 plankton 41 single celled organism 41 caverns 41 Saturn moon Enceladus 41 spherules 41 polar vortex 40 methane hydrate 40 hydrothermal activity 40 crevices 40 Saturn moon 40 Martian rocks 40 coral 40 deeps 40 amoebas 40 Earth crust 40 atmospheric nitrogen 40 kelp forest 40 Titan Saturn 40 seabeds 40 benthic 40 moss 40 volcanism 40 cryosphere 40 melting glacier 40 seamounts 40 crevice 40 sea squirts 40 marine invertebrates 40 marine reptiles 40 methane hydrates 40 hydrological cycle 40 Melting glaciers 39 landforms 39 lava 39 earth crust 39 colonizes 39 arctic 39 coral reef 39 upwelling 39 creatures 39 calcareous 39 Antarctic ozone 39 glacial melt 39 lakebed