Today I got a chance to take a really nice walk along the Lake Ontario shoreline in an area I had never walked before. However these are Zebra Mussel shells that have washed up on the beach and shoreline. All you could hear as you walked was "crunch crunch crunch". They are an invasive species that was first found in the Great Lakes in 1988 (probably brought in with ballast water of ocean-going ships by way of the Saint Lawrence Seaway).