Board Thread:Questions and Answers/@comment-28471956-20160526184703/@comment-25814498-20160531002723

Not quite. Essentially, he places two different signs on two different objects(or the same object) and when they come into contact they explode. There is no limitation saying that only people can be attached with the Sun sign, and chrollo himself doesn't need to set of the explosion. In the case of the referee, he placed one sign on his back and the other on his arm, then when commanded to do so, the referee made the two signs touch, thus causing an explosion.

Sun and Moon are two parts of the same bomb; when they come into contact they explode. There is nothing differentiating the two other than this fact; a Moon sign can only explode when in contact with a Sun sign, and a Sun sign can only explode when in contact with a Moon sign.