Before stars, the universe had only the three lightest elements: hydrogen, inert helium, and a bit of lithium. With just these building blocks, the complex molecules needed for life would not be possible (blog: Ode to Carbon).

Carbon, oxygen and the rest of the heavier elements came from the crucible of stars that died billions of years ago.

Here you see a light blue pellet of “dry ice” floating on a shallow bed of dark blue water and shooting off geysers of carbon dioxide as it warms up. The dry ice is solid CO2 which sublimates directly to gas as it warms up (skipping the liquid phase altogether).