This is an orange peeler:
It has a small spur used to score the skin of an orange for easier removal.
In writing terms, it’s like what your reader has to do to know your main character. At first, the character’s problem caused him or her to develop a tough skin. Once past that, the next layer is a web of complications and a mess to remove. That’s the conflict your character must work through:
By the time the middle is exposed, the transformation is complete, the character is nearly unrecognizable, and the book is all wrapped up: