This handout photograph taken in August 2016 and obtained on August 18, 2026 from Greenland Institute of Natural Resources shows the tusk of a narwhal in Scoresby Sound fjord system near Ittoqqortoormiit, East Greenland. Narwhals have nature's only straight tusk, a single tooth up to three metres long so strange they were sold as magical unicorn horns during the Middle Ages. On August 18, 2026, a large international team of researchers announced they had solved a long-running mystery about the tusks: how they get their uniquely spiralled yet arrow-straight form. (Photo by Mads-Peter Heide JORGENSEN / Greenland Institute of Natural Resources / AFP via Getty Images) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / Greenland Institute of Natural Resources / Mads-Peter Heide Jorgensen " - HANDOUT - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS