Maracas rockets are a music instrument 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 maracas rocket is stuck, it will burst after a few seconds, which can be dangerous.
There is also another type of maracas, which does not ignite but only amortize Rayman's jump, slightly going down and then returning to its original position. It's usually safer not to stay on them, as they're often placed above wrong notes.