Sea otters are known for their clever use of tools, and they often carry around rocks for several practical reasons. One of the main uses is for breaking open hard-shelled prey like clams, mussels, and sea urchins. They'll use the rock as a tool while floating on their backs, smashing the shells against it to access the soft meat inside. Additionally, sea otters have a loose patch of skin under their forearms that serves as a sort of pocket. In these pockets, they can store their favorite rocks