Priapulus caudatus (Lamarck, 1816)
Mouth with 7 rings each of 5 teeth. Introvert with 25 longitudinal ridges. Rest of body with numerous rings. A tail arise ventrally to the anus, bearing numerous vesicular branches.
Soft bottom up to at least 300 m.
Body usually 20-75 mm long, sometimes more.
Separate sexes. The females produce tens of thousands of tiny eggs, fertilisation is external and development is direct with larva called a lorica.