The term 'MARIMBA's Cousin' refers to two instruments, the Vibraphone (10 letters) and the XYLOPHONE (9 letters). The Vibraphone is a type of percussion instrument that consists of metal bars and produces sound when struck with mallets. It is similar to the MARIMBA, but has a motor-driven mechanism that creates a vibrato effect. The XYLOPHONE is also a percussion instrument made of wooden bars that are struck with mallets. It is similar to the MARIMBA in that it produces sound when struck, but it has a higher pitch than the MARIMBA. Both the Vibraphone and the XYLOPHONE are commonly used in jazz, classical, and popular music.