dry bottom of a reservoir covered with a layer of shells of bivalve mollusks cerastoderma and mytilus

bivalve mollusks dry mud cerastoderma mytilus tiligul estuary ukraine animal animals aquatic biology bivalves black sea cockleshell conch ecological ecology environment europe fauna halves hydrobiological hydrobiology invertebrate landscape life marine mollusc mollusk nature organisms saltwater shell seashell shellfish shells undersea water world wild wildlife worlds