Ocean microbes – plankton, algae, diatoms, bacteria, viruses (phages) – are a critical part of the carbon cycle of the ocean. Until recently, they were not very well understood.

Some great articles on the same:

https://mitei.mit.edu/news/ocean-microbes-display-hidden-talent-releasing-countless-tiny-lipid-filled-sacs

http://en.wikipedia.org/wiki/Marine_bacteriophage#cite_note-pmid17853907-11