Rocket-maracas are musical instruments found in Band Land. When Rayman jumps onto them, they ignite and expel their handle, and then start rising. It is possible to drive them by placing Rayman on the left or right edges. If the rocket-maraca is stuck, it will burst after a few seconds, which can be dangerous.
There is also another type of maraca, which does not ignite but only amortises Rayman's jump, descending slightly before returning to its original position. It's usually safer not to stand on them for too long, as they're often placed above wrong notes.