Answer: Trichuris trichiura, a.k.a. "whipworm"
As noted by Florida Fan, "we can clearly see the thread-like anterior portion and an inflated posterior, giving the worm resemblance to a whip". I always like to ask my students which end they think is anterior - they invariably (incorrectly) guess that it's the broader end! This gives me the opportunity to walk them through the life cycle and how the adult worms are embedded within the mucosa of the large bowel. It always seems to make more sense to them when I ask which end would be easier to thread into the wall of the bowel - the thin end or the thick end? This helps explain why the anterior end is thinner than the posterior. I also note that having a broader posterior end allows it to fill with eggs in the female worm, and these can then easily be shed into the intestinal lumen . I'm kind of old-fashioned, so my explanation is usually accompanied by some hand-drawn images.
And now for our poem by Blaine referencing the dreaded complication of whipworm infection - rectal prolapse!
When your booty's been turned inside-out
and you go to your doc to get it checked out
You'll feel yourself start to squirm
as he describes the culprit, whipworm
cuz Trichuris trichura like to let it to all hang out