A Pacific rock crab scuttling along the ocean floor will one day become a part of a vast, critical stash of carbon that lies off the coast of Northern California, which scientists have now measured for the first time.  This reserve holds untold millennia worth of the would-be greenhouse gas, according to a study released by the National Oceanic and Atmospheric Administration’s Office of National Marine Sanctuaries. The Pacific Ocean seafloor has exceptional carbon-caching prowess, highlighting the importance of leaving this hidden reservoir undisturbed, scientists say. Doug George, an ocean scientist with NOAA’s Office for Coastal Management who co-authored the study, is impressed by the “phenomenal amount of carbon trapped in just the top layers of the seafloor.”