Related by context. Frequent words. (Click for all words.) 65 hydrothermal vents 61 hydrothermal vent 55 oceanic crust 55 methane hydrate 55 steam vents 54 landforms 54 marine sediments 54 lavas 53 methane hydrates 53 moon Europa 53 volcanically active 52 Saturn moon Enceladus 52 ocean ridges 51 stromatolites 51 foraminifera 51 volcanic crater 51 volcanoes 51 oxygen isotopes 51 geologically active 51 Saturn moons 50 sedimentary rock 50 lithosphere 50 planetary nebula 50 Titan Saturn 50 molten lava 50 Martian landscape 50 solar nebula 49 basalts 49 ionised 49 polycyclic aromatic hydrocarbons PAHs 49 biogenic 49 icecaps 49 moon Titan 49 volcanic gases 49 continental crust 49 Weddell Sea 49 HD #b [002] 49 hydrothermal 48 microscopic organisms 48 aerosol particles 48 habitable planet 48 temperate forests 48 solar corona 48 seabeds 48 terrestrial ecosystems 48 geological formations 48 Saturn moon 48 extremophiles 48 Enceladus 48 magma chamber 48 regolith 48 geologic formations 48 ionized gas 48 volcanism 48 volcanic islands 48 silicates 48 hot Jupiters 48 rocky planets 48 subduction zones 48 subsurface 48 microscopic algae 48 organic molecules 48 lifeforms 47 lunar soil 47 limestone caves 47 planktonic 47 lava rocks 47 Earth crust 47 underwater caves 47 salt crystals 47 scarps 47 water vapor 47 polar regions 47 olivine 47 polar caps 47 astrobiologists 47 habitable planets 47 meteoroids 47 abiotic 47 volcanic 47 carbonaceous 47 ocean 47 rocky outcrops 47 lava tube 47 Polar Regions 47 landmasses 47 polycyclic aromatic hydrocarbons 47 kerogen 47 subarctic 47 single celled organisms 47 basaltic 47 liquid droplets 47 seamount 46 explosive eruptions 46 single celled 46 planets orbiting 46 lava 46 supernova explosion 46 archaea 46 moon Charon 46 super Earths