When the Covid-19 pandemic ends, you can thank the horseshoe crab for helping to save the world. This prehistoric creature’s blood contains a substance called Limulus amebocyte lysate (LAL), which is used to make sure medications and medical devices are germ-free. Pharmaceutical companies have used LAL for decades, collecting roughly 500,000 horseshoe crabs each year. Even though the crabs are returned to the ocean, thousands of them die in the process. And as the world cranks out Covid-19 vaccines, conservationists are concerned about the increased demand for horseshoe crab blood. Researchers have developed a synthetic alternative, but many manufacturers aren’t ready to abandon the tried-and-true method of testing with LAL. But whichever version they use, it’s clear that this ancient animal is playing a vital role in keeping humans safe. As microbiologist Allen Burgenson told Greenville News: “The world’s health care can thank the horseshoe crab.”