Can walls of oysters protect shores against hurricanes? Darpa wants to know.

On October 10, 2018, Tyndall Air Force Base on the Gulf of Mexico—a pillar of American air superiority—found itself under aerial attack. Hurricane Michael, first spotted as a Category 2 storm off the Florida coast, unexpectedly hulked up to a Category 5. Sustained winds of 155 miles per hour whipped into the base, flinging power poles, flipping F-22s, and totaling more than 200 buildings. The sole saving grace: Despite sitting on a peninsula, Tyndall avoided flood damage. Michael’s 9- to 14-foot storm surge swamped other parts of Florida.