When my kids were little, we used to pick up the broken ones and string them into necklaces. It was a fun activity for us.
Check out my silver and gold dipped broken pupu shell necklaces in my pre order section here:
- Rina @ Nostalgem
Ps. Ok so maybe I might have taken the idea from them 
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.PPS. Have you made necklaces out of shells with your littlies?