Horseshoe crabs: Ancient creatures who are a medical marvel

Correspondent Conor Knighton visits New Jersey beaches along the Delaware Bay to learn about horseshoe crabs – mysterious creatures that predate dinosaurs – whose very blood has proved vital to keeping humans healthy by helping detect bacterial endotoxins. He talks with environmentalists about the decline in the horseshoe crab population, and with researchers who are pushing the pharmaceutical industry to switch its use of horseshoe crab blood with a synthetic alternative used in medical testing.