21162 - Premium Grade Soft Bodied Xiphosurid (Horseshoe Crab Ancestor) Lower Ordovician Heterodiadema libycum indicating that this specimen has

indicating that this specimen has affinities with the depleted compositional group of shergottites

showing a perfect example of this Botryoidal crystallization typical of iron oxide

The mineralization is produced in agate

Some of them have glued or filled fractures

21162 - Premium Grade Soft Bodied Xiphosurid (Horseshoe Crab Ancestor) Lower Ordovician Heterodiadema libycum indicating that this specimen hasXiphosurans 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