Horseshoe crab blood is bright blue and more valuable than gold - worth about $60,000 per gallon!
The blue color comes from copper-based hemolymph instead of iron-based blood like humans have.
But the real value is in its amazing ability to detect bacterial contamination instantly. When horseshoe crab blood touches bacteria, it clots immediately.
Medical companies use this blood to test every vaccine, medical device, and injectable drug for dangerous bacteria. If horseshoe crab blood clots when mixed with a medical product, that product contains deadly contamination.
Every COVID vaccine was tested with horseshoe crab blood before approval. So was every flu shot, insulin dose, and surgical implant.
The crabs are carefully harvested - about 30% of their blood is drawn, then they're released back into the ocean. Most survive this process.
Four hundred thousand horseshoe crabs are bled annually for medical testing, making this one of the strangest industries on Earth.
Scientists are trying to create synthetic alternatives, but so far nothing works as well as the real thing. These living fossils with blue blood have become essential to modern medicine!