That heart shape you see on all the photos? Its congealed nitrogen flowing- slooooowly over the surface at -400f. Cold. To walk on it would be like stepping onto a ocean of something about as solid as toothpaste. Hence- you see it so clean..anything rocky from the skies like a meteor just sinks.
What does it all mean? It means that there might be forms of life out there that can thrive on extreme chemicals and temperatures. If not little Pluto..then the other countless planets in the big Universe.
Might be earth like people somewhere out there who have liquid nitrogen blood,look at pink skies and have red "snowflakes". Just like a Beatle song.