Phoronida
- Illustration of the internal anatomy of a horseshoe worm and a list of species.
- http://www.tolweb.org/Phoronida/2493

Phoronida World Database
- Commonly known as horseshoe worms, this phylum is an exclusively marine group of lophophorate animals. Provides a searchable taxon tree.
- http://www.vliz.be/vmdcdata/phoronida/

Introduction to the Phoronida
- Introduction to the Phoronida, a small phylum related to brachiopods and bryozoans.
- http://www.ucmp.berkeley.edu/brachiopoda/phoronida.html