The world around us is wonderful, fascinating, and, sometimes, inconceivable. "The most beautiful thing we can experience is the mysterious" said Albert Einstein, and I could not agree more with him. One of the greatest satisfactions in life is to reveal the arcana of Nature which nobody knew before, to add a little bit to the giant body of the human knowledge. This book is about such quest - understanding the properties of new elementary particle called X(3872). This particle might be an example of a new form of matter made out of 4 elementary constituents (quarks), rather than out of 2 or 3 quarks, like regular matter is. The physicists have a hard time trying to explain the behaviour of X(3872) within 2-quark model. In this work the nature of X(3872) is explored by looking at the properties of its decay products. Also, an overview of X(3872)''s known characteristics is given and different possibilities within 2- quark model, as well as within other models, are discussed.