black silhouette of three types of molluscs: cephalopod, gastropod, bivalve.

mollusks molluscs cephalopod gastropod bivalve educational material biology zoology octopus three variety snail shell air-breathing land mollusc animal fauna vector white background isolated anodonta cygnea anodonta freshwater toothless clam duck mussel unio crassus unio mollusk seashell roman helix pomatia helix black silhouette graphic line