Main characters

• Shelldon Clam (voiced by Tabitha St. Germain) is a young Yoka star shell who lives in a hotel called the Charming Clam Inn with his family. He likes helping his friends and solving problems.
• Herman (voiced by Richard Ian Cox) is a blue hermit crab with an immense infatuation with "alien" artifacts and "paranormal" events. He has a crush on a classmate Hurly.
• Connie is a money cowry who works at the Charming Clam Inn, so she could do more than rely on her parents' money.

Recurring characters

• Dr. Shell (voiced by Lee Tockar) is a brilliant yet scatter-brained riversnail inventor and a guest in the Charming Clam ever since it was set up and has become something of a permanent resident there. He has traveled widely across the seas in search of inspiration but is not interested in making money, only the social benefits his inventions bring to others.
• Mama Clam (voiced by Ellen Kenndy) is a magnolia crocus clam who lives and runs the Charming Clam Inn with her husband and three children. She is a cool-headed wife and mother who is not easily daunted by hardship or challenges. Raised in the cut-throat, fast-paced Shell City, Mama Clam is savvy, a careful planner who always seems to know the perfect solution to a problem.
• Papa Clam (voiced by Colin Murdock) is a muddy-brown crocus clam that lives in and runs the Charming Clam Inn with his wife and three kids. He is guileless, none too bright, and crass at times. He is easily frazzled by setbacks and his solutions to problems tend to border on the impractical.
• Mr. Inkysquid (voiced by Scott McNeil) a small squid who is Shelldon's gang’s school teacher.
• Cracken a wealthy sea slug businessman.
• Nikki Nautilus a nautilus TV celebrity with a cult following amongst the youngsters in Shell City.
• Luther a loggerhead sea turtle who drives a taxi.
• Click and Clack two hyperactive Yoka star shells who are Shelldon's cousins.
• Hook, Sam and Mack a trio of heavy metal-addicted fishes, Hook is a Nkhomo-benga peacock, Sam is a sockeye salmon and Hook is a mackerel.
• Stan Starfish a purple starfish who is a bully at Shelldon's school.
• Captain 8-Ball a octopus pirate who lives inside of a sunken ship.
• Louise a friendly humpback whale that gives Shelldon advice.
• Dr. Bao a Chinese Haliotis discus with herbal knowledge.
• Emperor Ehru a fiddler crab who lives on a small island.
• Crabby a Christmas Island red crab who is the owner of the neighbourhood bookstore.
• Mugsley a sly hermit crab who is Cracken's henchmen.
• Napoleon a mantis shrimp that talks in a high-pitched voice.
• Wilbur a goofy seagull.
• Mayor Yoka a Yoka star shell who is Shell Land's mayor.
• Baft and Thwart a duo of greedy human scuba divers that don’t care what damage they do to the ocean or marine life.
• Shello Polo a Mexican Yoka star shell who talks to Shelldon as a ghostly figure.
• Mrs. Prim is a prissy crystal red shrimp who obsesses over her nails and hair, which causes her to forget about her peers.
• Hurley is a pink sea snail that sometimes appears in the show. She has a crush on a classmate named Herman.

Season 1

Season 2

Season 3