PLEASE help! What do you call this kind of never-ending picture?? PLEASE answer!!?

Do you know that kind of picture that never end?

For example, a boy is standing on a ship, holding a book, and on the book is the same picture, a boy on a ship with a book, and the book has the same picture, and on and on it continues...

I'll give another example:

A girl is wearing a shirt with a picture of her wearing the shirt, which has her wearing the shirt which shows her wearing the shirt, etc, and it never ends.

PLEEEEAAASE HELP!!!!!!!!!!!!!!!!!!!!!