You get a box of shells (and later, when you get well good, trilobites, those little whiskery arthropods that look like woodlice) and organise them by generation, observing one change per step in the family tree. A pattern might change in one direction, for example, or a shape might flip in another. Maybe a triolobite gets a different number of segements, or some cool little horns. It’s very satisfying. And after each box you solve, you get to keep a fossil!
