Scientists from Pennsylvania State University and the National Oceanic and Atmospheric Administration stunned oceanographers in 1997 when they found centipede-like worms living on and within mounds of methane ice on the floor of the Gulf of Mexico, about 150 miles south of New Orleans. The worms apparently feed on bacteria that digest methane rising from below the seafloor. The oxygen-depleted conditions inside the mounds would kill most forms of sea life. Such discoveries have given rise to new theories about conditions under which life might originate on other planets.