Balanoglossus is a genus of ocean-dwelling acorn worms. It has zoological importance because, being hemichordates, they are an "evolutionary link" between invertebrates and vertebrates. Balanoglossus

The acorn worms or Enteropneusta are a hemichordate class of invertebrates. The closest non-hemichordate relatives of the Enteropneusta are the echinoderms. There are 111 known species of acorn worm i