Have you ever held a handful of scallop shells and wondered why they are colored differently? Or where the holes in a clam shell came from? And what is a mermaid's purse, exactly? Here's a fun guide ...

This story was originally published August 2017. Maybe collecting shells is a favorite pastime of yours, but you don’t know which is a moon snail and which is a mud snail. Or, you’re walking along the ...