Scooby-Doo! Mystery Incorporated Season 2 Episode 4 Revenge of the Man Crab
During a volleyball tournament down at the Crystal Cove beach a giant crab beast attacks those who are present. The beast kidnaps Daphne which places Fred in a state of total shock rendering him unable to say anything that doesn't relate to her. The gang receives an old newspaper article from Mr. E about four kids who disappeared in the Crystal Cove caves many years prior. The gang manages to capture the "man crab" and to save Daphne. When Velma shows her the newspaper article from Mr. E, Daphne realizes that two of the kids in the newspaper photo are the same kids as in the picture in the locket she had found in the Crystal Cove caves.