Hexabranchus aureomarginatus Ostergaard,
|shows closeup of the anal
papilla (center), the nephridiopore (small opening on left) and a small
tubercle of unknown function (just to the right of the anal papilla);
the nephridiopore is on the right side of the papilla and the tubercle
is on the left side of the papilla from the
perspective of the animal
Photos: John Horn: north shore, Kauai; Sept. 8, 2022.