Seashell (noun)

1. The hard protective outer layer of certain marine animals, such as mollusks and crustaceans, that have died and washed up on the shore.
2. A decorative item made from the hard protective outer layer of certain marine animals.

Origin:

From the words sea, meaning the large body of salt water, and shell, meaning the hard protective outer layer of certain animals, combined to form seashell, meaning the hard protective outer layer of certain marine animals.

Examples:

1. She collected seashells from the beach and used them to decorate her living room.
2. The seashells on the beach were of various shapes and sizes.
3. I found a beautiful seashell while walking on the beach.
4. The conch seashell is a popular decorative item.
5. The specimen of seashell was identified as belonging to a species of oyster.