Balanoglossus in Mashail Island described it as a worm-like holothurian. The discovery of gill-slits in this animal by Kowalewsky (1865) led to creation of a special class Enteropneusta by Gegenbaur (1870). Bateson (1885) included them in Phylum Chordata. Hyman (1959), however, placed them near Echinodermata and gave Hemichordata a status of an independent phylum. This simple organism shows affinities with several diverse groups. Balanoglossus is a tuberculos or burrowing and exclusively marine animal. It is found in shallow waters between tide marks along the coast of warm and temperate oceans. Balanoglossus clavigerus is a U-shaped excavated in a sandy bottom Nemertines
Tullimonstrum characteristics of the well-known modern phyla, it was speculated that it was representative of a stem group to one of the many phyla of worms that are poorly represented today. Similarities with Cambrian fossil organisms were noted. Chen "et al." suggested similarities to "Vetustovermis planus". Others pointed to a general resemblance between "Tullimonstrum" and "Opabinia regalis", although Cave "et al." noted that they were too morphologically dissimilar to be related. In 2016 a morphological study showed that "Tullimonstrum" may have been a basal vertebrate, and thus a member of the phylum Chordata, with one study suggesting "Tullimonstrum" may be closely