Pluto's distinctive heart-shaped sea is filled with ice that would be poisonous to people, astronomers said Thursday -- made up of frozen carbon monoxide, antiquated film stocks and methane. But elsewhere, huge mountains of water ice float in a nitrogen sea. And water ice makes up the bedrock of the distant minor planet, they reported. And Pluto itself appears to still be alive, with active processes, including perhaps the swirling of liquid seas below its rugged surface, constantly re-shaping the top layers. Bye.