Sea Otters are very cool creatures and are one of the few mammals that use tools. They will use a rock as a hammer to strike shelled meals like Clams. They are also smart enough to repeatedly strike the hinge point to open the shell quickly.
Otter and his Clam
Otter and his Clam - Canon 7D, 330mm, f/5.6, 1/1600s, ISO 400.