This planktonic foraminifera called Orbulina universa evolved about 13 million years ago. The single-celled, shelled organism was captured by scuba divers from surface waters off Santa Catalina Island, CA.

Living inside the calcite spines of this creature are other simple organisms called dinoflagellates; the dinoflagellates have formed a partnership with the foraminifera, using photosynthesis to produce foods while living in the calcium-rich spines.

At the end of their four-week life cycle, the shells from both protists (foraminifera and dinoflagellate) sink to the seafloor where they become part of the microfossil assemblage in deep-sea sediments. The geochemical compositions of such shells are used to reconstruct past ocean changes. Researchers reported in the Jan. 26 issue of the journal Science Express the importance of such geochemistry; they reported that lithium isotopes in sea sediments reflect several intense episodes of mountain-building and other major geologic events in the last 60 million years.