Reflections, Wells harbour

Beautiful light in Wells this morning. This boat is a regular feature, and I liked the way it was reflected in the pools left by the retreating tide. Many hundreds, probably thousands, of pink-footed geese going overhead in long, straggling skeins, but sadly couldn't photograph them well enough with the phone. What I did photograph (see extra) was a strange bubbly mass on the beach - there were quite a few clumps of this stuff on the sand. Any idea what it might be?