The writer is a science commentator
Horseshoe crabs are among the oldest species on Earth. The prehistoric-looking creatures, more closely related to spiders and scorpions than crustaceans, have existed for about 450mn years.
But most fascinatingly, they have bright blue, copper-based blood valued in the region of $16,000 a litre. That is because it has unique biological properties: it clots quickly in the presence of bacterial toxins, making it a now-vital ingredient in the safety testing of drugs and vaccines.
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