Neogloboquadrina pachyderma help improve reconstructions of past ocean temperatures. Credit: Adele Westgård / UiT The Arctic University of Norway"> Laboratory experiments on the planktonic foraminifer Neogloboquadrina pachyderma help improve reconstructions of past ocean temperatures. Credit: Adele Westgård / UiT The Arctic University of Norway Tiny plankton shells used to reconstruct past polar ocean temperatures may contain two different chemical stories, a new study by iC3 researchers has found. The work shows that Neogloboquadrina pachyderma, a key species in polar climate archives, can grow an outer shell crust with a different chemical make-up from the shell beneath it, even when both are grown in the same conditions. The paper is published in the journal Geochimica et Cosmochimica Acta . This discovery could help scientists produce more accurate records of past ocean change. A shell with two stories N.…