Phoronidea is a term used to describe a group of marine animals that have a horseshoe-shaped lophophore. Some synonyms for phoronidea include phoronids, horseshoe worms, and phoronid worms. These animals are often found in marine sediment and have a soft, elongated body. The phoronid worms filter feed on plankton and other small particles, using their lophophore to capture their food. While not as well-known as some other marine animals, phoronids play an important role in the marine ecosystem and have unique characteristics that make them fascinating to study.