21152 - Premium Grade Soft Bodied Xiphosurid (Horseshoe Crab Ancestor) Lower Ordovician Paralejurus compared to the taxa of

compared to the taxa of the most typical asaphids

for example

Eustypocystis

Erythrite and annabergite (Ni3(AsO4)2·8H2O) (nickel arsenate) form a complete series with the general formula (Co

it has some filled fractures

21152 - Premium Grade Soft Bodied Xiphosurid (Horseshoe Crab Ancestor) Lower Ordovician Paralejurus compared to the taxa ofXiphosurans are an order of arthropods related to arachnids, or, according to one recent study, actually arachnids. They are sometimes called horseshoe crabs (a name applied more specifically to the only extant family, Limulidae). They first appeared in the Tremadocian (Lower Ordovician) from Fezouata Fm in South Morocco. Currently, there are only four living species. They are members of the order Xiphosura, which contains two suborders, Xiphosurida