Best and worst planets.

[Wyrd of Gawd]

Whatever planets sentient life evolved on would be the best planets for these beings to live on.

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Deep sea ecology: hydrothermal vents and cold seeps

Instead of sunlight, vent life relies on hydrogen sulfide - more commonly known as rotten egg gas and toxic to most land-based life.

Since the discovery of vent ecosystems dependent on hydrogen sulfide, scientists have found similar communities living around these so-called ‘cold seeps’. Others have also been found that rely on methane instead of hydrogen sulfide. Some of these are around bizarre deep-sea lakes called 'brine pools': depressions in the sea floor filled with water that has a much higher concentration of salt then the surrounding water. And recently a tube worm community was found living on solid methane hydrate on the ocean floor.

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Sentient beings who evolved to rely on hydrogen sulfide or methane would regard the surface of Earth as a shitty place to live.

But will they have opposable thumbs and the Internet?