A sanderling checking out an arthropod shell along Limantour Beach in Point Reyes. Unfortunately for the bird, there didn't appear to be much edible material left. After picking at it briefly for a short time, it gave up and moved on. These shells are pretty common along the beach, although I'm not sure which species it belongs to (it's a bit more visible in the second shot below).
When I saw this shell in a nice place right above the water line with a flock of sanderlings working their way towards me, I decided to set up by it to see if the birds would be interested. A few came close to it but decided not to stop, but then this one curious sanderling spent maybe 30 seconds or so investigating it. I was pretty happy with the potential of the shots like the one below, but when I was reviewing the images the top shot really stood out for me with the out of focus sanderling taking off in the background.