Content: 1. Authors 2. Dataset description 3. Experimental methods 4. Attribution 5. Licence 1. Authors Adrian Rodriguez-Palomo, Peter Alling Strange Vibe, Dimitra Athanasiadou, Jonas Palle, Leonard C. Nielsen, Jonathan T. Avaro, Thorbjørn Erik Køppen Christensen, Nina Kølln Wittig, Mads Ry Vogel Jørgensen, Innokenty Kantor, Manfred Burghammer, Jiliang Liu, Stefano Checchia, Christian Appel, Karl Anker Jørgensen, Eva Garde, Mads-Peter Heide Jørgensen, Marianne Liebi, Henrik Birkedal. 2. Dataset description 2.1. This dataset contains: Raw data: scanning_XRD-integrated_data.zip: Integrated intensity for synchrotron scanning X-ray diffraction on thin narwhal tusk slices from Narwhal #1 and Narwhal #2. Data measured at the DanMAX beamline from the MAX IV synchrotron, Sweden. scanning_SAXS-integrated_data.zip: Integrated intensity for synchrotron scanning small-angle X-ray scattering on thin narwhal tusk slices from Narwhal #1 and Narwhal #2. Data measured at the cSAXS beamline from the Swiss Light Source at the Paul Scherrer Institute, Switzerland. These data can also be found in full in DOI: 10.16907%2Fcdcbc412-d7bc-41ea-82f5-32922ddfa0fd. SAXS_tensor_tomography-projections.zip: Synchrotron small-angle X-ray scattering tensor tomography of tusk cylinders with a voxel size of 150 µm, 25 µm, and 3 µm. HDF5 files with the scanning projections at multiple rotation and tilt angles [3]. Data measured at the cSAXS beamline from the Swiss Light Source at the Paul Scherrer Institute, Switzerland, and at the beamlines ID13 and ID15A from the European Synchrotron Radiation Facility, France. These data can also be found in full in DOI: 10.15151/ESRF-ES-699731854 for ID13 and DOI: 10.15151/ESRF-ES-1112065501 for ID15A. birefringence_microscopy.zip: Polarized light birefringence microscopy on thin narwhal tusk slices from Narwhal #1 and Narwhal #2. Images containing the intensity, retardance in nm and fast-axis angle. Data measured at Chalmers University of Technology, Sweden. mechanical_tests-3_point_bending.zip: 3-point bending tests of ~1 mm2 section tusk rods extracted from the longitudinal and radial orientations. Sample ID numbers 132-142 are radial. Sample ID numbers 146-155 are longitudinal. Data measured at Aarhus University, Denmark. tusk_morphological_measurements.zip: Data measured at the Greenland Institute of Natural Resources, Greenland, by Aarhus University, Denmark. Processed data and results: scanning_XRD-results.zip: Rietveld refined parameters as previously described in [1] for synchrotron scanning X-ray diffraction on thin narwhal tusk slices from Narwhal #1 and Narwhal #2. Data measured at the DanMAX beamline from the MAX IV synchrotron, Sweden. scanning_SAXS-results.zip: SAXS orientation and anisotropy analysis following [2] for synchrotron scanning small-angle X-ray scattering on thin narwhal tusk slices from Narwhal #1 and Narwhal #2. Data measured at the cSAXS beamline from the Swiss Light Source at the Paul Scherrer Institute, Switzerland. SAXS_tensor_tomography-results.zip: Reconstructed 3D orientation, degree of anisotropy and main intensity using the Mumott software v1.2 [https://mumott.org/] for synchrotron small-angle X-ray scattering tensor tomography of tusk cylinders with a voxel size of 150 µm, 25 µm, and 3 µm. Data measured at the cSAXS beamline from the Swiss Light Source at the Paul Scherrer Institute, Switzerland, and at the beamlines ID13 and ID15A from the European Synchrotron Radiation Facility, France. 2.2. Sample identification for the X-ray experiments: ID Narwhal # Sex Orientation Shape Thickness Diameter x Length XRD SAXS SASTT Birefringence 001 1 Male Transversal Thin slice 28 µm - X X - - 002 1 Male Transversal Thin slice 29 µm - X X - - 003 1 Male Transversal Thin slice 40 µm - - - - X 008 1 Male Transversal Thin slice 50 µm - - - - X 009 1 Male Longitudinal Thin slice 36 µm - X X - - 010 1 Male Longitudinal Thin slice 43 µm - X X - - 022 2 Male Transversal Thin slice 42 µm - X X - - 027 2 Male Transversal Thin slice 40 µm - - X - X 028 2 Male Longitudinal Thin slice 35 µm - X X - - 029 2 Male Longitudinal Thin slice 45 µm - - X - X 031 2 Male Radial Cylinder - 1x3 mm - - X - 037 2 Male Transversal Thin slice 50 µm - - X - - 041 2 Male Transversal Thin slice 35 µm - - - - X 058 2 Male Radial Cylinder - 245x430 µm - - X - 108 2 Male Radial Cylinder - 4.55x6.75 mm - - X - 2.3. References: [1] S. Frolich & H. Birkedal. J. Appl. Cryst. 48, 2019-2025 (2015). DOI: 10.1107/S1600576715020099 [2] O. Bunk, M. Bech, T. H. Jensen, R. Feidenhans, T. Binderup, A. Menzel & F. Pfeiffer. New J. Phys. 11 123016 (2009). DOI: 10.1088/1367-2630/11/12/123016 [3] M. Liebi, M. Georgiadis, A. Menzel, P. Schneider, J. Kohlbrecher, O. Bunk & M. Guizar-Sicairos . Nature 527, 349–352 (2015). DOI: 10.1038/nature16056 3. Experimental methods Experimental details and methods descriptions can be found in the associated publication: A. Rodriguez-Palomo, P. A. S. Vibe, D. Athanasiadou, J. Palle, L. C. Nielsen, J. T. Avaro, T. E. K. Christensen, N. K. Wittig, M. R. V. Jørgensen, I. Kantor, M. Burghammer, J. Liu, S. Checchia, C. Appel, K. A. Jørgensen, E. Garde, M.-P. H. Jørgensen, M. Liebi, H. Birkedal, "The narwhal tusk assembles its macroscopic helix from building blocks with opposing twists", Nature Communications (2026). 4. Attribution Please cite the associated publication and dataset as:A. Rodriguez-Palomo, P. A. S. Vibe, D. Athanasiadou, J. Palle, L. C. Nielsen, J. T. Avaro, T. E. K. Christensen, N. K. Wittig, M. R. V. Jørgensen, I. Kantor, M. Burghammer, J. Liu, S. Checchia, C. Appel, K. A. Jørgensen, E. Garde, M.-P. H. Jørgensen, M. Liebi, H. Birkedal, "The narwhal tusk assembles its macroscopic helix from building blocks with opposing twists", Nature Communications (2026). Multimodal X-ray imaging and mechanics dataset for the narwhal tusk © 2026 by A. Rodriguez-Palomo, P. A. S. Vibe, D. Athanasiadou, J. Palle, L. C. Nielsen, J. T. Avaro, T. E. K. Christensen, N. K. Wittig, M. R. V. Jørgensen, I. Kantor, M. Burghammer, J. Liu, S. Checchia, C. Appel, K. A. Jørgensen, E. Garde, M.-P. H. Jørgensen, M. Liebi, H. Birkedal. Zenodo (2026). DOI: 10.5281/zenodo.15089410 5. License Multimodal X-ray imaging and mechanics dataset for the narwhal tusk © 2026 by A. Rodriguez-Palomo, P. A. S. Vibe, D. Athanasiadou, J. Palle, L. C. Nielsen, J. T. Avaro, T. E. K. Christensen, N. K. Wittig, M. R. V. Jørgensen, I. Kantor, M. Burghammer, J. Liu, S. Checchia, C. Appel, K. A. Jørgensen, E. Garde, M.-P. H. Jørgensen, M. Liebi, H. Birkedal is licensed under CC BY-NC-SA 4.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/4.0/