Are seashells a living thing

The actual seashell is not living, it is a hard, protective outer layer made by an animal that lives in the sea. The shell is not part of the body and was never living.

The common seashell is produced by a mollusc, and by the time the shell reaches the shore, the invertebrate has been eaten or rotted out, leaving the more durable exoskeleton - the seashell.