Hanuman's adoration and devotion for Rama was unique. he not only helped find Sita, whom Ravana, the king of Lanka, had abducted, but also acted as Rama's messenger requesting Ravana to return Sita and repent for the sin. Enraged Ravana set Hanuman's tail on fire. With this burning tail, he set the whole of Lanka aflame. He also helped Rama build a bridge of stones through deep seas, assisting him cross over to Lanka. In the battle that ensued between Rama and Ravana, Hanuman played a major role, ensuring that the evil Ravana was destroyed.
This is the monkey god's most popular and widely worshipped iconic image. He tears open his chest to display Rama and Sita who reigned supreme in his heart. His crown, armlets, bangles, etc., are studded with stones. The mace that lies next to him is also rich in grandeur. His long legendary tail towers high above. The face wears a devotional look and the eyes hold inexplicable genteel. He kneels in a sacramental position, which strengthens the fact that he considered himself the humble servant of Lord Rama.
Devotees of Rama, as well as those of Hanuman, hold this image in high esteem and invoke their blessings by worshipping Hanuman's idol or image by smearing it with vermilion.
This description by Renu Rana.