noun

The word "shell" can have a couple of different meanings, depending on what you're talking about. Here are the two most common ones
Hard Outer Covering: This is the shell you might find on an animal, like a turtle's shell or a crab's shell. It's the tough, protective case that the animal carries around with it.
Eggshell: This is the hard outer layer of an egg. It protects the chick or baby animal inside until it's ready to hatch.

Example

1. The hermit crab found a bigger shell to move into.
2. Be careful not to crush the egg's shell when you're cooking.
3. I collected some pretty seashells on the beach.