Living snow; even for the Doctor, that’s a bit of a surprise. It talks too; talking snow is even better. The Doctor loves encountering new things. He’s seen so much in the past nine hundred plus years, it’s good to know he hasn’t yet seen everything there is to see.
Not good snow though. That’s a pity. Why does everything new turn out to be an evil intelligence intent on invading the planet and conquering its inhabitants? There must be something in the water.
And of course there is: a tragically frozen governess. Damn it! Now he’ll have to investigate.