pop-up element
OAB Definition
From the BARD website:
Pop-up elements are shapes, images, or objects that rise away from the base page spread of a book. They are animated by turning the page in a book. Pop-ups that are cut out of the base page itself transform from a flat folded sheet to a fully 3-dimensional shape at 90 degrees and lays flat again when open to 180 degrees. There are also pop-ups that are fully extended only when the book is open to 180 degrees; these are created by paper elements that have been added on to the base page.