This crystal is needed to verify the truth of any fact about this universe. He hears statements that were uttered at a distance of less than 42 centimeters, and changes his color depending on whether they are true. If the statement is true, it glows green; if false, it glows red. It may also turn yellow if your question is inaccurate and the answer can be both "yes" and "no" This crystal never speaks, it can only change color and remain silent.