As well as being one of the strongest muscles in the human body, the tongue has another interesting quality. Similar to fingerprints, humans also have unique tongue prints!
The tongue is a unique organ in that it can be stuck out of mouth for inspection, and yet it is well protected in the mouth and very difficult to forge. The tongue also presents both geometric shape: information and physiological texture information which are potentially useful in identity verification applications. Furthermore, the act of physically reaching or thrusting out is a convincing proof for the liveliness.
Picture Credit : Google