When Elbone ventured to create shell jewelry as his new business in "Puff Enuf", he formed an attachment to a particularly large shell which he named Shelly. He painted a face on it and it became another imaginary companion of his alongside Rocky.
In "King Burple", Shelly was temporarily lost when Elbone's houseboat was blown away when he tried using a wooden anchor. When the Rescue Riders helped him find his boat, he rescued Shelly from being picked at by a number of seagulls. She rode home next to Rocky on the wooden anchor.
Shelly is a weathered, large clam shell with a mouth and two eyes painted on it.