Nannoconus, a major marine planktonic biocarbonate producer of the Early Cretaceous (150–120 Ma), biomineralized heavy (200–1400 picogram) skeletons (5–20 μm) of interlocking lamellae spanned around a central canal, by an unknown process. With the first-ever application of synchrotron-based ptychographic X-ray computed tomography (PXCT) of nanometric resolution, we reconstructed the 3D skeleton by combining segments of lamellae and inferred its possible biomolecule(s)- “templated” calcification.

The coccoliths are major contributors to the particulate inorganic carbon in the ocean. They are extremely difficult to weigh because they are too small to be manipulated. We propose a universal method to measure thickness and weight of fine calcite using polarizing microscopy that does not require fine-tuning of the light or a calibration process. This method named "bidirectional circular polarization" uses two images taken with two directions of a circular polarizer.

Calcareous nannoplankton are photosynthetic plankton producing micrometric calcite platelets having a fossil record covering the past 200 Myr. Based on species richness, platelets size and abundance we observed four evolution phases through time: Jurassic–Early Cretaceous invasion phase of the open ocean, Early Cretaceous–K–Pg extinction specialization phase to the ecological niches, post-K–Pg mass extinction recovery and Eocene–Neogene establishment phase with domination of a few small species.