Moon snails Polinices lewisii are distinctive components of sand/mud substrata, noticeable not just because of their large size, but also because of their distinctively shaped egg collars.

NOTE  it doesn’t take much imagination to figure out why these globular shells are called “moon” snails.  They are common inhabitants of intertidal and subtidal sandy areas.  They are harvested as food in some areas, but are reportedly not particularly tasty, which probably explains why they are still relatively common. One author, however, would probably take exception to this comment regarding taste. She says that a "delicious" broth can be made by steaming the meat in its own fluids and an edible, but tough, "piece of variant meat" can be produced by frying the animal alive in butter.  Better still, she states that "no ill effects...were felt from that consumption" referring, one assumes, to herself and not to the snail being fried alive.  As for the notion that the meat is poisonous, the author reminds us that west-coast First-Nations shell middens are often well populated with moon-snail shells.