Marimba - soft sound. Xylophone - hard sound.
Non-pitched percussion instruments are used for a few reasons, providing a beat and a cool backbone to the song. Pitched percussion instruments are usually used for harmony or the melody of a song, they don't have that backbeat that a snare or a bass has, and a snare and a bass don't have the melody to the song, such as a Marimba would.
The marimba is a musical instrument in the percussion family that was developed in Mexico. These are usually made from wooden bars with resonators which are struck with mallets to produce music.
The maracas.
Percussion instrument.
Although the tuning fork is not usually thought of as a musical instrument, technically, it would be classified as a percussion instrument.
Some percussion instruments may, and some may not. Usually if something like a drum has tuning equipment, it may be tuned to whatever pitch you desire.
There are different kinds of percussion instruments, and they have different tone colors. A snare drum makes a high-pitched, sudden, and fairly sharp sound when hit with a drumstick. The timpani are tuned instruments, and usually hit with soft mallets rather than drumsticks, so their sound is more "rounded" and mellower, as well as much lower in pitch. The orchestra bells are pitched instruments, with keys made of metal, that are usually hit with fairly hard mallets, so the sound is somewhat sharp and bright; the xylophone has similar keys, but they are made of wood, so the sound when they are hit is somewhat - well, woodier. It is not as bright or as sharp as hitting metal, and usually softer in volume. Pianos are also percussion instruments, and they can make quite a few different tone colors.
A musical percussion instrument (drum); usually consists of a hollow cylinder with a membrane stretched across each end.
Percuss is a medical term, to strike. When the doctor percusses your chest, she is striking it. So a percussion instrument is struck, mainly. There are others that you can shake, rattle or stroke, but they are usually struck.
sansa is an instrument in which you pluck some (usually 16-27) thin metal rods sticking out of a wooden box. It is a traditional African instrument.
To generalize somewhat. There are many different types of percussion instruments. A percussion is basically any musical object that you hit with a stick to make a sound. A drum is usually a rounded piece of wood or metal with a plastic, cloth, or vinyl on top that is hit to produce a sound. A triangle is a percussion instrument and is a piece of metal shaped like a triangle with a gap in one corner. A xelephone has different shaped blocks that are hit to make different pitched sounds. Cymbals are flattened pieces of metal shaped into a circle. A piano is also considered a percussion instrument. The list goes on and on.
It is a musical instrument, usually circular in shape which has a surface for percussion and also has several metal jingles attached to it.