Horseshoe crab underwater over under photo

060606, Arthropods: Arthropoda, Barnacles: Cirripedia, Crustaceans: Crustacea, Invertebrates, Marine Life, Tide Pool, copyrighted, estuary, horseshoe crab: Limulus polyphemus, marine, ocean, over-under: under/over: under-over: split: split perspective: ha, underwater, underwater photo

An extract from the horseshoe crab’s copper based, blue blood is used to test that any injectable medication used on humans is free of bacteria infection.