Pistachios wallop walnuts as the toughest nut to crack
sciencemag.org
sciencemag.org
"Topological Interlocking and Geometric Stiffening as Complementary Strategies for Strong Plant Shells" [1]
also contributed to by the scientist mentioned in the article. It has pictures, graphs, cross sections and other data for all you nutcracking enthusiasts out there.
[1] https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202004...