The
Sipuncula or
Sipunculida (common names
sipunculid worms or
peanut worms) is a group containing 144–320
species (estimates vary) of
bilaterally symmetrical,
unsegmented marine worms.
Sipuncula signifies "little tube or siphon." Traditionally considered a
phylum, they might be a subgroup of phylum
Annelida based on recent molecular work.