- A shell is a covering around the body of a shelled animal
- Covering something is a kind of protection
- So, a shell is a kind of protection for some animals

- A shell is a kind of protection for some animals
- Therefore, the shell of an animal is used to protect the animal

- A shell is a part of a snail
- A snail is a kind of animal
- Hence, a snail is a kind of animal that has a shell

- The shell of an animal is used to protect the animal
- A snail is a kind of animal that has a shell
- Hence, a shell is a part of a snail for protecting the snail

Therefore, a shell is a part of a snail for protecting the snail
[Question]A snail's shell provides the snail with
[Context]- A shell is a covering around the body of a shelled animal 
- Covering something is a kind of protection 
- A shell is a part of a snail 
- A snail is a kind of animal