Ochre Sea Stars (Pisaster ochraceus) often assume a hunched appearance when they're feeding, holding their prey below their bodies.
In the photo above, at first I thought this sea star might be interested in the Lined Chiton (Tonicella lineata) attached to the rock below the sea star's arm on the upper left. (To find the chiton, look for the pink and white stripes.)
But then I noticed something darker directly underneath the sea star, and wondered if the sea star was eating something else — A mussel? A limpet? I couldn't tell for sure, but this image also made me wonder if the chiton could sense the sea star nearby and whether it would try to make a "getaway" while the sea star was preoccupied?
Only the sea star and the chiton know the outcome.
P.S. If you're curious about the chiton, I posted a picture of a Lined Chiton on 9 November 2012, and a related Loki's Chiton on 17 May 2013.