Zach the fish loved to swim in the fresh sea. His shiny fins helped him zoom fast through the waves.

"Zach!" shouted Fiona the frog. "I found something very strange!"

Zach flipped his tail. "Show me this thing, Fiona!"

Fiona hopped over to a sunken ship. "This ship has thousands of shells inside!"

Zach's eyes grew wide. "I think that's a treasure ship!"

They swam inside the ship. The roof had a big hole, and the floor was fuzzy with seaweed.

"Look at these shells!" said Zach. "Some are smooth, some are sharp!"

"This one feels soft," said Fiona as she touched a shell.

Just then, they heard a "thump, thump" sound. Something was moving in the shadows!

"Who's there?" asked Zach with a shiver.

Out came Thelma the thin turtle, wearing a sheriff's badge!

"Freeze!" shouted Thelma. "These shells are under my watch!"

Zach and Fiona gasped. "We're sorry! We thought nobody owned them."

Thelma laughed. "I'm just having fun with you! These shells are free for everyone to share."

So Zach, Fiona, and Thelma spent the day sorting shells. They found five that whistled when you blew on them, seven that shone like the sun, and three that smelled like vanilla!

"This is the best ship ever!" said Zach.

"Even better than finding gold," said Fiona.

And every Thursday after that, they visited their ship and found new treasures to share with their friends.