What is this ?
My son is completing his science project on our local tidepools. We've identified all specimens during our field study, except for the attached. Can you help?
This is Norrisia norrisi, commonly known as Norris' Top-shell or Norris's Topsnail.
By the way, on its surface in one of your photos are two Crepidula norrisiarum, also known as slipper limpets.
Howard/Berry Chair and Curator of Malacology Henry W. Chaney, Ph.D.