Boulders are grey rocks that generally get in your way. Most are mobile, and the player with have to either jump them, duck them, or bust them with a Strength Boost (There are some specifically large ones where this doesn't work). The player can ride on larger boulders - called boulder-riding - to earn points. Many boulders are not mobile and the player can only run over them. There are special rocks that mark the endings of Challenge levels. For Level 1, the ending rock is simple; a small stone with a flower next to it. For level 2, the ending rock is a taller rock with a small pebble in front of it. For level 3, it is a large, square boulder with a smaller one leaning against it. For level 4, it is two square rocks leaning against each other. For level 5, it is a stone wheel, the kind that cartoon cavemen are often seen riding. For level 6, it is a long, flat rock balanced on two smaller ones. For Apocalypse (this only applies to Insane! because on Easy, Medium and Hard, Apocalypse is the last level and ends with a sanctuary), the ending rock is a large, circular rock balanced on a pointy one. Ending rocks are not mobile, and stand in the background, so the player can only run past them. All ending rocks have an arrow sign (shaped like >) somewhere on them, marking a"proceed"