Anyone wanna write a short expository paragraph about why turtles have shells?

Turtles have shells evolved from ribs. Turtles and other animals with shells use their shells like shields to protect themselves from predators, or animals that hunt them. Turtles needed a shield on their backs and stomachs because they faced predators in the ocean from both above and below.

Shells evolved from ribs ... Turtles and other shelled creatures use shells like shields to protect themselves from predators, or animals that hunt them. Turtles probably needed a shield on their backs and stomachs because they faced predators in the ocean from both above and below.