Introduction to the Sipuncula: The Peanut Worms
These animals, which are commonly called "peanut worms" because some have the general shape of shelled peanuts, are not particularly well studied. Only about 320 species have been formally described, all marine and mostly from shallow waters. While some (like the specimen of Sipunculus shown below) burrow into sand and mud, others (like this unidentified species from French Polynesia) live in crevices in rocks, or in empty shells. Still others bore into rock.
Publisher - University of California Museum of Paleontology
Subjects - Sipuncula, Peanut Wormhttp://www.ucmp.berkeley.edu/sipuncula/sipuncula.html
Citation: Collins AG. 2000. Introduction to the Sipuncula: The Peanut Worms. Berkeley, CA: University of California Museum of Paleontology. http://www.ucmp.berkeley.edu/sipuncula/sipuncula.html