"Then he saw the worms. Phylum Annelida, he remembered them from biology class."

Phylum Annelida
Creative Commons AttributionPhylum Annelida - Credit: Comrogue, Flickr
Phylum Annelida are segmented worms, a class that includes both earthworms and leeches. They can be recognised by their multiple circular segments, with both circular and longitudinal muscle fibres.