The existence of ample amounts of hydrogen in the subsurface ocean of Enceladus indicates that microbes--if any exist there--could use it to obtain energy by mixing with carbon dioxide dissolved in water. This particular chemical reaction, termed methanogenesis, because it manufactures methane as a byproduct, may have been of critical importance in the emergence of life on our planet.
There is a bizarre rocky landscape, well hidden from our prying eyes, in the secretive shadows under the oceans of our Earth. Here, in this strange and alien domain, it is always as dark as midnight. Thin, tall towers of craggy rock emit billows of black smoke from their peaks, while all around the towers stand a weird, wavy multitude of red-and-white, tube-like organisms--that have no eyes, no intestines, and no mouth. These 3-foot-long tubeworms derive their energy from Earth itself, and not from the light of our nearby Sun--a feat that most biologists did not believe possible until these wormish creatures were discovered back in 2001. The extremely hot, superheated black water, billowing out from the hydrothermal vents erupting on Earth's seafloor, provides high-energy chemicals that sustain the tubeworms, as well as other weird organisms that apparently thrive in this very improbable habitat.
So, the next time you're planning a big fishing trip, make sure you know when the moon sets and rises for that day and plan around it. You will find your fishing experience a much more rewarding one for having that bit of knowledge. I promise!