Shelby & Watts. Tide Pool Troubles.

"There isn't a mystery that Shelby & Watts can't solve! They're saving the environment, one case at a time ... When Shelby gets a letter from Fred the hermit crab claiming that all the shells are missing from the beach, she and Watts are just the duo to help him. With Shelby's deductive skills and Watts's scientific knowledge, there's no case the two of them can't solve--one environmental mystery at a time"--Provided by publisher.