| The fin rays sprouting from the ends are also unique in having a long, stiff unsegmented basal area. |
| Slugs and snails have a soft, unsegmented body measuring 2 to 4 cm in length. |
| The developmental mode of polychaetes is characterized by the production at hatching of an initially unsegmented trochophore larva. |
| Sipunculans, or peanut worms, have an unsegmented body with a retractable introvert. |
| Flatworms are unsegmented, bilaterally symmetrical worms that lack a coelom but that do have three germ layers. |
| These unsegmented worms have been found in Cambrian rocks, such as the legendary Burgess Shale. |
