Hemichordate

Template:Taxobox begin Template:Taxobox begin animalia Template:Taxobox subregnum entry Template:Taxobox phylum entry Template:Taxobox end placement Template:Taxobox end Hemichordata is a phylum of deuterostome animals, generally considered the sister group of our own, the chordates. They date back to the Lower or Middle Cambrian and include an important class of fossils called graptolites, most of which became extinct in the Carboniferous. One surviving species is known, Cephalodiscus graptolitoides.

All other modern forms are marine worms, commonly called acorn worms. They are divided into two classes: the Enteropneusta and the Pterobranchia.