Why Birds Are the World's Best Engineers
https://www.nytimes.com/2020/03/17/science/why-birds-are-the-worlds-best-engineers.html?action=click&module=Editors%20Picks&pgtype=HomepagePaper: Mechanics of randomly packed filaments--The "bird nest" as meta-material
https://aip.scitation.org/doi/10.1063/1.5132809(a) Grains jammed by multiple boundaries under gravity in a grain silo.44 (b) A structure jammed solely by the bottom wall and gravity made up of Z-form shapes.45 Reproduced with permission from Murphy et al. Archit. Des. 87, 74?81 (2017). Copyright 2017 John Wiley and Sons. (c) A bird's nest stable without any external forcing or boundaries. Poquillon et al., J. Mater. Res. 40, 5963?5970 (2005). Copyright 2005 Cambridge. (d) A piece of cotton fiber stable without any external forcing or boundaries. Copyright 2008 licensed under a Wikimedia Commons CC-BY-SA 3.0 License.4
Sticks in a cylindrical experiment at the Goodyear Polymer Center at the University of Akron in Ohio, where Hunter King investigates the engineering of birds nests.