We were lucky enough to take a day trip to the beach this summer. The beach is my whole family’s happy place. The waves, sun, sand, saltwater…a day enjoying the sights, sounds, tastes, smell, and feel of the beach is the perfect de-stressor and reset.

One of my kids’ favorite things to do at the beach is collect seashells. We have hundreds of seashells sitting in buckets in our backyard. I searched for a STEAM activity that used seashells, and when I saw this project on Pinterest, I knew it would be an activity that my kids would love!


Note on Borax: If it is handled properly and used according to the directions in the amounts and procedures specified, it is not dangerous in solution. Please have an adult handle the Borax and wash your hands thoroughly after coming in contact with the Borax and/or wear rubber gloves. Do not allow the Borax to come into contact with skin, eyes, or ingest it.

Borax has been used in science experiments for years, but there are reports that Borax is an unsafe ingredient to use with children. I have read both sides (read a case against Borax here and a case for Borax here), and I personally feel that this experiment was safe under supervised use for my children. I handled the Borax, and my children only came into contact with it while observing the crystals. I made sure they washed their hands with soap after touching the crystals.


  • Seashells
  • 1 cup Borax powder
  • 4 cups water
  • Measuring Cups
  • Pot
  • Glass container
  • Magnifying glass (optional)


  1. Bring 4 cups of water to boil.

2. Add 1 cup of Borax, stir until completely dissolved. If the Borax all dissolves easily add more, 1 tablespoon at a time. You want the solution supersaturated, where the Borax will no longer dissolve in it.

3. Arrange the seashells concave side facing up in the bottom of a glass container, making sure none of the seashells are touching.

4. Carefully pour the hot Borax solution into the glass container, add enough so the seashells are completely covered in liquid. Set aside where it won’t be disturbed.

5. Watch the crystals grow on the seashells. You can leave them in the solution for anywhere from a day to up to two weeks. We left our seashells in the solution for two weeks to grow our large crystals.

6. Carefully remove your seashells from the solution and set on a paper towel to dry.

7. Observe the crystals on the seashells. Where did they grow? Did they grow on both sides of the seashell or just one side? Use a magnifying glass to get a closer look at the crystals.


  • Science: By adding heat we were able to add more borax than is normally soluble in water creating a supersaturated solution. As the supersaturated solution cools, crystals begin to form in two ways. First the Borax will come out of the solution forming precipitate, which will fall to the bottom of the glass container and stick to the seashells. Second, as time elapses water will evaporate out of the solution making it even more supersaturated, so more Borax will precipitate out and join the growing crystals on the seashells. 
  • Math: Practice measurement and counting while adding ingredients. 

This was an easy activity to set up, the hardest part was patiently waiting for the crystals to grow! My kids LOVE their seashell crystals and both have some saved in their rooms. The excitement and joy in my kids faces over seeing the fully formed crystals made my heart happy. I love how they are learning about new science concepts and finding ways to reuse items from nature in new ways.

Our crystal covered seashells
The backs of the seashells did not grow crystals because the precipitate collected on the side facing up

Are you going to try growing seashell crystals after reading this? What other household items or items from nature do you think crystals would grow on?


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