Description: Data files S1-S13. Microfocus X-ray Computed Tomography cross-sectional images of 13 selected radiolarian skeletons in the western Arctic Ocean. The CT-scanned 3D images can be visualized by 3D image viewer Molcer Plus (http://www.white-rabbit.jp/molcerPlusE.html). Data file S1. Microfocus X-ray Computed Tomography cross-sectional images of Actinomma boreale Data file S2. Microfocus X-ray Computed Tomography cross-sectional images of Actinomma leptodermum leptodermum Data file S3. Microfocus X-ray Computed Tomography cross-sectional images of Actinommidae spp. juvenile form Data file S4. Microfocus X-ray Computed Tomography cross-sectional images of Amphimelissa setosa adult form Data file S5. Microfocus X-ray Computed Tomography cross-sectional images of Amphimelissa setosa juvenile form Data file S6. Microfocus X-ray Computed Tomography cross-sectional images of Joergensenium arcticum adult form Data file S7. Microfocus X-ray Computed Tomography cross-sectional images of Joergensenium arcticum juvenile form Data file S8. Microfocus X-ray Computed Tomography cross-sectional images of Nassellarida indet. Data file S9. Microfocus X-ray Computed Tomography cross-sectional images of Phormacantha hystrix Data file S10. Microfocus X-ray Computed Tomography cross-sectional images of Pseudodictyophimus clevei Data file S11. Microfocus X-ray Computed Tomography cross-sectional images of Pseudodictyophimus gracilipes gracilipes Data file S12. Microfocus X-ray Computed Tomography cross-sectional images of Pseudodictyophimus spp. juvenile form Data file S13. Microfocus X-ray Computed Tomography cross-sectional images of Spongotrochus glacialis