This is an episode that first aired in 2018 and then again in the thick of the pandemic in 2020. Why? Because though Horseshoe crabs are not much to look at, beneath their unassuming catcher’s-mitt shell, they harbor a half-billion-year-old secret: a superpower that helped them outlive the dinosaurs, survive all the Earth’s mass extinctions, and was essential in the development of the COVID vaccines. And what is that secret superpower? Their blood. Their baby blue blood.And it’s so miraculous that for decades, it hasn’t just been saving their butts, it’s been saving ours too. But that all might be about to change. Follow us as we follow these ancient critters - from a raunchy beach orgy to a marine blood drive to the most secluded waterslide - and learn a thing or two from them abouthow much we depend on nature and how much it depends on us. Radiolab is supported by listeners like you. Support Radiolab by becoming a member ofThe Lab(https://members.radiolab.org/)today. Our news...