Researchers at the University of California San Diego have figured out how to turn algae into flip flops. They founded a startup to sell the shoe, but face a challenge in getting their invention mass produced: There aren't enough algae farms to support the startup's supply chain.
https://www.youtube.com/watch?v=9otWnmTpQAQ
https://www.businessinsider.com/algae-flip-flops-sandals-biodegradable-2021-2