Samba de Amigo Maracas
From Sega Retro
The maracas are able to send a signal back to the Dreamcast, telling the console the position of the controllers and how often they are being shaken. Samba de Amigo had six positions for where the maracas could be held (three for each hand) - high, medium and low. There is an extra sensor attached to each lead which will record the position.
The Wii version of the game did not ship with maraca controllers as it tracks positions via the Wii remote, however Sega did bundle the game with a set of maraca shells which, when placed on the Wii remote and nunchuk, will rattle when shaken.