Over two billion years
back in the past
the Earth’s like a snowball
with frozen white crusts.

The carbon dioxide
levels were low
which made our world colder
and covered in snow.

Life had evolved as
small single cells.
But many would die
as the temperatures fell.

Since some could survive
that long glacier spell,
could other ice worlds
hide life-forms as well?

First published in Double Helix (Jul 2016)

Reproduced with permission of CSIRO

www.doublehelix.csiro.au