10 seen, feeding in ephemeral paddock wetland
Sipunculid. Approximately 100 specimens collected.
It extended a striped neck.
I think. . . Some kind of worm.
Living in a 1/2" shell, which it could move around; actively feeding in nearby sand.
This worm, which I think is Themiste pyroides (Burrowing Peanut Worm), was between some rocks with what I think is Paranemertes peregrina (Mud Nemertean) and some Green Ribbon Worms, as you can see in the second photo.
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. Traditionally considered a phylum, they might be a subgroup of phylum Annelida based on recent molecular work.