little bivalves are attaced to a rams horn or spirula spirula

spirula rams horn float cephalopods molluscs mollusc buoyancy chambered spirulidae little post squid aillight beachcombers beachcombing buoyant attached ride substrate bivalves mollusk sea ocean sand beach shore shoreline grain grains hitch hitchhiker washed unfortunate tide tidal current shell line bad choice floatation dead water environment coast coastal seashore anchor pelagic oceanic anchored life