Bouncing rocks are dangerous blue objects from the original Rayman game, Rayman Junior and Rayman Designer which are only found in the Caves of Skops. They usually rebound on the ground or above the void, and can be used to reach high up places. Like spiky platforms, Rayman must avoid all contact with their sides and their lower part.
In Rayman Designer and its spin-offs, there are two types available as events, both of which can be used in the Mountain and Cave worlds. The first one, titled Bouncing rock, bounces in place while the other one, titled Jumping rock, jumps to the right.