This is pretty philosophical stuff for a comic book of this era. Superman says 'this isn't life as I or anyone else knows it, so it's not life'. Swamp Thing says 'how the hell would you know? Life takes infinite different forms - just because you don't understand what this new form is doesn't mean it's not life. This is something new to the world - don't destroy it! Who are you to say that it's not life, when neither you or anyone else understands how their OWN life works?' OK, so that last bit was me extrapolating. But still.