Class Echiura
Defining Characteristic - Muscular organs (anal sacs) outpocketing from the rectum into the coelomic space, bearing numerous funnels that discharge coelomic fluid, and possibly wastes, through the anus.
Live in sandy or muddy burrows, or sometimes in rock crevices.
~140 spp., in shallow marine waters.
Most conspicuous feature is an anterior cephalic projection called the proboscis, which may be many times longer than the rest of the animal - used for gathering food.