It is my intuitive guess
that in the early life of universe there must be
pure single element planets for every element of
our periodic table. We may still find some pure
diamond stars, gold stars, silver stars, water
stars etc. Making and breaking of galaxies and
black holes is creating planets of mix elements.
The life came to our earth
form some other planet and will move on to many
other planets. Just imagine the case when our
earth will breakup in several pieces after some
gigantic asteroid will hit it. Many living
creatures, plant seeds will be carried away to
remote places of universe packed with frozen sea
water. Some of ice packed carriers of living
cells will find a new earth waiting to begin its
civilization.
