Damru Made of Wood

Damru is one of the attributes of Lord Shiva. The sound of Damru is the sound of Omkara. Amazing thing about Damru is, it gives one beat at a time, the chords at both ends strike at the same time, and how many times you play it, it gives same beat every-time, no variations; yet, its sound can go high and low but sound goes in the same beat. The beat of Damru symbolizes the sound of Aum, the all pervading sound, which also has the only one beat without any variations,  that is existing since the infinity. When Lord Shiva plays Damru, He plays Omkara, and when He dances with it, he is called Natraja.
 
Damru symbolizes the Universe which is always expanding and collapsing. From an expansion it collapses and then it re-expands, this is the process of creation. If you see your heartbeat, it is not just one straight line but it is a rhythm that goes up and down. The whole world is nothing but rhythms, energy rising and collapsing to rise again. So the Damru signifies that. Look at the shape of the Damru, from expansion it collapses and again expands. The Darmru is also a symbol of sound. Sound is rhythm and sound is energy. The whole universe is nothing but a wave function, it is nothing but rhythms.