Horseshoe crabs: Ancient creatures who are a medical marvel

Correspondent Conor Knighton visits New Jersey beaches along Delaware Bay to learn about horseshoe crabs—mysterious pre-dinosaur creatures—whose very blood has been shown to be vital to keeping humans healthy by helping detect bacterial endotoxins. He talks to environmentalists about the decline in horseshoe crab populations and to scientists who are pushing the pharmaceutical industry to replace the use of horseshoe crab blood with a synthetic alternative used in medical testing.