This is about birds in that I was looking for Surfbirds along a Monterey, California, wharf when I heard the pounding noise. In the water to my left was a Sea Otter. It had a plate-sized crab balanced on its stomach. The otter had broken the large claw from the crab and was using it as a hammer to pound open the shell and expose dinner, assault of the crab with its own part adding insult to injury. The otter used a two-handed -- so to speak -- downstroke to batter the clam, large claw clasped between front paws. You can see the claw in the photos here. The otter eventually quit pounding and began eating, gnawing on the claw leg for openers. The crab slowly wagged its remaining legs as the otter ate. I did find a Surf Bird a few minutes later. This was seen during a Christmas visit to California.
The otter is rolling over. The crab claw and its attendant leg is held between the otter's paws.
The otter is gnawing on the leg removed from the claw, which can be seen in the center of the photo.
Here is the Surfbird, a winter visitor to the Pacific Shore from British Columbia to South America.