cockel shells clinging to beach rock at low tide

acorn attached barnacles bay beach beaches bivalve calcite cardiidae clam clams clinging close coastal cockel cockle cockles coral cornwall crustacean detritus edible encrusters feeders food hard heart hermaphroditic impermeable low macro marine molluscs mussel mussels nature ocean plankton radial rock rocks rounded saltwater sea seafood seaweed sessile shallow shaped shells sheltered shore south stalk sticking stone strong substrate sunlight suspension tidal tide water waters west