X-ray phase-contrast CT images of a diatom fossil pasted on a glass fiber. (a) 3D rendered view, (b) virtual cross-sectional image perpendicular to the rotation axis, (c) virtual cross-sectional image parallel to the rotation axis, (d) line profiles of the region between arrows A and B in (b) (black line) and arrows C and D in (c) (gray line), respectively. Voxel size is 175 nm × 175 nm (H) × 172 nm (V). Horizontal scan pitch is 175 nm, exposure time is 15 ms and dwell time is 20 ms. Number of projections is 501 for 180° rotation. Total measurement time for tomographic scan is approximately 90 min.