Biologist Sönke Johnsen is studying one of the darkest things on the planet, which is almost like holding a black hole in his hands. He is trying to understand how something can be so black. His research takes him to microscopic forests where gold appears black, and to the deep sea where it meets the moon. He also explores places that seem empty but are actually full. In this episode, it is mentioned that dragonfish are not the ones with teeth that slide back into their skull, but rather fangtooth fish, although both can be ultra-black. There are other animals that are equally as dark, including butterflies, wasps, and birds. Vantablack is no longer the blackest man-made material. The episode is hosted by Molly Webster, who also reported and produced the episode with help from others. The episode features original music and includes credits and citations for the research and music used. Radiolab is a podcast supported by listeners and foundations, and encourages listeners to follow them on social media and share their thoughts.