The remarkable properties of a recently-discovered squid protein could revolutionize materials in a way that would be unattainable with conventional plastic. Originating in the ringed teeth of a squid’s predatory arms, this protein can be processed into fibers and films with applications ranging from health-monitoring ‘smart’ clothes to self-healing recyclable fabrics that reduce microplastic pollution. Materials made from this protein are eco-friendly and biodegradable, with sustainable large-scale production achieved using laboratory culture methods.