 Qytosan and Qytin are two biopolymers derived from crustaceans which have been used to create passive radiative cooling materials. These materials have the ability to absorb and emit radiation in the mid-infrared spectrum, allowing them to act as thermal insulators and reduce the amount of energy transferred into the environment. Additionally, these materials are biocompatible and non-toxic, making them ideal for use in passive cooling applications. This article was authored by Tobias Lauster, Anika Mowell, Kai Herman, and others.