Graptolites
Graptolithina is a class in the animal phylum Hemichordata, the members of which are known as graptolites. Graptolites are fossil colonial animals known chiefly from the Upper Cambrian through the Lower Carboniferous (Mississippian).  The name graptolite comes from the Greek graptos, meaning "written", and lithos, meaning "rock", as many graptolite fossils resemble hieroglyphs written on the rock.