Fascinating.
Horseshoe crab blood is a bright blue liquid valued at $60,000 per gallon because it contains a copper-based protein (hemocyanin) and a clotting agent called LAL (Limulus amebocyte lysate). LAL instantly clots when it touches bacterial endotoxins, making it an FDA-mandated safety test for virtually all vaccines and injectable drugs.
They have hemocyanin in their blood and we have hemoglobin.
I wonder if they're any beneficial uses for hemoglobin to them like their hemocyanin is to humans. :wo: