Mesolimulus walchiJurassicSolnhofen, Germany Horseshoe crabs are not crabs at all but rather a xiphosurid arthropod with blue blood that are more closely related to spiders and scorpions and a close ancestor to trilobites. Horseshoe crabs (Mesolimulus) are very rare in the fossil record with the best preserved specimens such as this one being found in the 150 million year old lithographic limestone of Solnhofen, Germany. This golden Horseshoe crab, Mesolimulus walchi is complete with outstanding with the complete animal being in a raised 3-D preservation. Matrix measuring 10 1/2 x 8 x 1 in. Crab measuring 5 in