'Phytoplankton are responsible for most of the transfer of carbon dioxide from the atmosphere to the ocean. Carbon dioxide is consumed during photosynthesis, and the carbon is incorporated in the phytoplankton, just as carbon is stored in the wood and leaves of a tree'.

The air we breathe is processed by Phytoplankton

https://earthobservatory.nasa.gov/features/Phytoplankton#:~:....