Geothermal activity. i wish i could tell you we know it's life. bill: because it is, what, it's organic, right? >> it's an organic molecule. we don't know yet where it comes from. we're trying to figure this out using a remote-controlled robot, so it's a difficult thing. finding the meth their tell -- methane tells you there's something going on there. bill: organic does not necessarily mean this is alive, right? >> exactly. methane gas is something that shouldn't be there, so the fact that it's there tells you something act you have is happening -- active is happening. that's the next thing w...