What are those gray toilet plungers on the beach?

It’s a question often asked of our beach naturalists when they volunteer on local shorelines during low-tide days each summer. The photo below offers a great hint. The animal is a moon snail, and the gray “plunger” is the snail’s egg case. They’re a common sight on Seattle beaches in the summertime, and they are commonly mistaken for litter. They look like rubber, but they are actually made of sand, with a middle jelly layer that contains the snail’s eggs. The mother moon snail turns upside down to lay her egg mass, and as it emerges, the mother’s mucous adheres sand to the outside of the egg mass, and the collar shape forms as she moves her shell and foot. The eggs (roughly 500,000 of them) take about six weeks to hatch.

Moon snail


In the photo below, you can see a microscopic peek inside that egg collar (for a chance to check out the microscope that captured the image, visit the Aquarium for Family Science Weekend, May 28-30!).

Moon snail


Another common sight on the beach that invites questions? Clamshells, like the one pictured below, with sunken holes near the hinges. How do the holes get there? Perhaps you guessed it—they’re the work of moon snails. They use their radula (or rasp-like structure of tiny teeth) to drill holes in clamshells—then it’s clam on the half shell for lunch!

Moon snail


Interested in learning more about the amazing creatures on local beaches during low tide? Join Seattle Aquarium beach naturalists this summer! They’ll be stationed at a dozen Puget Sound shorelines on low-tide days throughout the summer. Click here for the complete schedule, locations and accurate directions.

Support the Seattle Aquarium

Your support connects people to the ocean in a way not otherwise possible and inspires bold action to care for animals and protect our shared marine environment.