Hard sci-fi novel where "snowfall" is made up of microscopic creature skeletons

Question

I remember reading a hard sci-fi novel. somewhere along the way the protagonist is part of a group that finds itself trapped in a building by what they originally mistake as a heavy snowfall. The "snow" is revealed to be made up of microscopic alien creature skeletons that fell (I think) from space. I think the snow was something of a harbinger of a menacing alien threat, and was a prelude to a showdown with a much nastier baddie. I wish I remembered more; I recall the book having a dark, desperate overtone, my like my search for the identity of the book itself.

Sorry for vagueness, any guess appreciated.

P.S. Fisk's Trillions wasn't it, but thanks for the suggestions.

Answer 1

I don't remember this as being hard sci-fi, but could you be thinking of Nicholas Fisk's Trillions?

It's a short novel in which a town is covered in a heavy fall of what looks like snow but is actually made up of trillions of microscopic interlocking creatures. Most of the story revolves around understanding them, what they are, what they want, what they're doing on Earth and why.

Trillions were hard, bright, tiny things which suddenly arrived, millions and millions and millions fo them, one windy day in a village called Harbourtown.

No one could explain them, much less why they had suddenly arrived. Were they a blessing, as their beauty suggested, or a deadly, inexplicable threat? A boy with a microscope was just as likely to come up with the answer as all the acknowledged experts in any known kind of science, so somehow it seemed natural for two 'ordinary' boys, Scott and Bem, to join forces with an ex-spaceman against the frightening efforts of the ruthless General Harman to destroy the Trillions, no matter what the cost.