How do sea otters use tools to break open shellfish?

Sea otters are known for their use of tools, which they use to crack open shellfish and other prey like crabs and clams. They typically use rocks, which they place on their stomachs while floating on their backs, to strike and break open shells. The otters use their strong forepaws to manipulate the rocks and ensure the food inside is accessible. This ability to use tools is an example of their advanced problem-solving skills and is one of the few known cases of tool use in non-human animals.