The Sea Snail (Caenogastropoda) is a clade of marine (saltwater) gastropod molluscs, including a few freshwater snails and land snails. 

The Sea Snail includes periwinkles, cowries, wentletraps, moon snails, murexes, cone snails, and turrids. 

The Sea Snail has a single auricle (chamber) in its heart, and a single pair of gill slits for breathing. 

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM