Summer means the ocean and seashells for us! We like to get creative with our summer science experiments so we had to try this crystal seashells borax science experiment, which is actually an easy science experiment to set up! Simply mix the solution and set aside. Over the course of 24 hours, you can observe some neat changes! Growing crystals on seashells is an awesome STEM project for kids!


make crystal seashells

Grow Crystal Seashells Overnight!

There are super cool ways to explore the sciences for each season! For summer, we decided to experiment with growing borax crystals on seashells. Our seashells came from a beach, but you can easily pick up a bag of shells to try this at home if you don’t live near the beach.

Make science exciting for kids by finding fun ways to introduce science learning.  Growing crystals is perfect for an easy chemistry experiment you can set up at home or in the classroom. Learn about saturated solutions, suspension liquids, ratios, and crystals!

See the crystal growing process with this video below. Just change out shells for pipe cleaners!


This crystal sea shells activity makes a fun science craft that you can even display. These crystals are pretty hardy even for little hands. This isn’t a very hands-on science activity for young kids due to the chemicals involved, but it’s great for practicing observation skills. You can always try growing salt crystals as a safe alternative for the younger scientist!

Looking for easy to print activities, and inexpensive science experiments? 

We have you covered…

Click below to get your quick and easy science activities. 

Crystal Seashells Borax Crystal Growing Experiment


Growing borax crystals on seashells only require two ingredients, water, and powdered borax {found in laundry detergent aisle}. You will need a handful of shells and a flat container. The seashells should not touch each other.

Check out the bottom of this page for alternative ways to grow crystals with kids!


  • Borax Powder {found in laundry detergent aisle}
  • Water
  • Measuring Cups and Tablespoon
  • Spoon
  • Mason Jars or Glass Containers
  • Seashells


The most important part of growing these fun crystal seashells is mixing up a saturated solution. The saturated solution will allow the crystals to form slowly and correctly.  A saturated solution is a liquid that is filled with particles until it can no longer hold any more of the solid.

We need to get our water hot first in order to make the best saturated solution. As the water heats up the molecules move away from each other allowing the solution to hold more of the borax powder.

STEP 1: Boil Water

STEP 2: Add 3-4 Tablespoons of borax powder per 1 cup of water.

I would make a 3 cup solution to get started if you are going to do several seashells. When you are mixing the solution, you will still see a tiny bit of the powder floating around and settling to the bottom. That means it’s saturated!

STEP 3: Place your seashells in glass containers {glass prevents the solution from cooling down to quickly}

STEP 4: Add the solution to the glass containers and make sure to completely cover the shells.

STEP 5: Put it aside and observe what happens.

Crystal Seashells borax Crystal Growing Summer Science Experiment and Activities


Crystal seashells is a suspension science experiment. When the borax is mixed with hot water, it remains as solid particles in the water. As the water cools, the particles settle and form the crystals. Pipe cleaners are also popular for growing crystals. Check out how we made a crystal rainbow with pipe cleaners.

As the solution cools down, the water molecules come back together forcing the particles out of the solution. They land on the nearest surfaces and continually build up to form the perfectly shaped crystals you see.  Make sure to take note of whether the borax crystals look the same or different to each other.

If the solution cools down too quickly, the crystals form irregularly because they don’t have a chance to reject the impurities that are also contained in the solution. You should try to leave the crystals untouched for about 24 hours.

After 24 hours, you can take the crystal seashells out and let them dry on paper towels. Set up an observation station for the kids to look at the crystals. Have them describe what they look like and even draw them!

Did you know you can also Dissolve A Seashell for more cool chemistry? Click here.

Crystal Seashells Science Experiment for growing Crystals with Borax Powder

Our crystal seashells still look lovely after a few weeks if left undisturbed. My son still enjoys examining them from time to time. He also shows them off to guests when we have company! There are so many ways to engage in simple science at the beach and while you are there, pick up extra seashells to grow crystals on too!

Crystal Seashells Borax Crystals Summer Science Activity


We used seashells we found on a beach vacation! This is a fun way to extend a favorite vacation. Or use the natural materials around where you live! Check out this crystal evergreen branch we tried.

Next time you are at a beach, bring a handful of shells home. Craft stores also sell seashells. Growing crystal seashells is perfect early learning science that has wonderful visual results!




Cool and easy to set up summer science experiments!

Simple summer science experiments and activities for kids including outdoor science activities.

Even more ocean science fun for kids!

We have a complete lineup of real ocean science experiments, projects, and activities the kids will love!

Ocean science activities for kindergarten and preschool ocean theme and beach learning. Make ocean slime, beach discovery bottles, sand slime, wave bottles, measure shells, grow crystal seashells, and more summer science ideas for kids.

Looking for easy to print activities, and inexpensive science experiments? 

We have you covered…

Click below to get your quick and easy science activities. 



  1. No where that I can see do you talk about the issues of safety around borax. This is something I pulled off the web:
    Borax is quite popular online these days. It’s in recipes for everything from children’s craft concoctions to alternative cleaning products and homemade baby wipe solutions. Before you use it, though, make sure you know all the facts.

    Borax, which is also known as Boric Acid and is sold under the brand name “20 Mule Team,” is often touted as safe and natural. While it is a naturally occurring mineral, that doesn’t mean it is without dangers.

    Borax is often recommended as a “safe” pesticide, fungicide and cleaner, but it is officially classified as a poison. Government sites recommend that people who work with Borax use gloves and handle it with caution. Studies have linked it to reproductive problems in some lab animals, as well as a host of serious disorders at higher levels.

    Boric acid is an acute eye and respiratory tract irritant, which is quite toxic if ingested. In addition, it is unavailable in parts of Europe because of concerns that it caused birth defects and problems with the reproductive organs of children. It is recommended that pregnant women and children in particular do not have exposure to Borax.

  2. Do you know if you spray a clear lacquer on them if they will stay longer? I think these would be beautiful glued on a frame or something and was trying to figure out how to preserve them…

  3. I know someone tried doing that recently but I don’t know the longterm answer yet. These do last a suprsingley long time.

  4. Found you through Pinterest! This looks like so much fun. My little is too little for science experiments yet but my niece is quite the scientist and I think we will try this when she comes to visit next.

  5. May I ask how you prevented the bottom portion of the shell from growing crystals? Did you coat it with something?

  6. I didn’t do anything to the shells! Did you have a different result? The crystals just grew where they wanted to grow.

  7. I’m not sure where you read this but borax and boric acid are two entirely different things.

  8. Borax and Boric Acid are two different things yes, but they are still from the borate family. I will go in and clarify. Thank you.

  9. I have had good luck with spraying with clear acrylic sealer, I have also dipped them in clear polyurethane and let them set and dry on plastic wrap. The clear spray is less mess, and easier. The poly gives them a really neat “under glass” type effect. But both ways make for long lasting crystals.

  10. You do not need to but can. You can also set it up as an experiment and do one without lid and one with lid.

Comments are closed.