Young Brunette Girl Reveals Her Seashell Necklace And Tan Lines In The Sand On The Rocky Beach

Although there are a number of species of shelled mollusks that are quite large, there are vast numbers of extremely small species too, such as micromollusks.
Not all mollusks are marine however, there are numerous land and freshwater mollusks, for example snail and freshwater bivalves. And not all mollusks have an external shell: some mollusks such as some cephalopods (squid and octopuses) have an internal shell, and many mollusks have no shell, for example slug and nudibranch.
• Bivalves
Bivalves are often the most common seashells that wash up on large sandy beaches or in sheltered lagoons. They can sometimes be extremely numerous. Very often the two valves become separated.