Appeared on earth 450 Million years ago, this horseshoe-crab (its nickname) has hardly evolved. And their blue blood is simply prodigious: it clots in contact with bacteria to prevent contamination of the animal. And this blue blood is used in hospitals to detect bacteria on implants and medical equipment. 500,000 Limules are caught every year by laboratories for a 30% blood sample. The price per litre is 11,000 Euros! This specimen comes from Indonesia, it is a Carcinoscorpius Rotundicauda. And this display: eclate de Beauchêne, makes it possible to understand the complexity of the joints of this marine animal.