Hazrat Mahdi (as) has the ''Seal of Prophethood'' on his shoulder

We understand from the hadiths that Hazrat Mahdi (as) will have a clear sign on his back, between his shoulders, as in the Prophet’s (saas). This sign is known as the “the Seal of Prophethood.”

Hazrat Mahdi (as) will have the sign of prophethood on his shoulder as the Prophet (saas) did. (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar, p. 41)

The sign of the Prophet (saas) is on his shoulder. (Al-Barzanji, Al-Isha'ah li-ashrat al-sa'ah, p. 165; Al-Muttaqi al-Hindi, Al-Burhan fi Alamat al-Mahdi Akhir az-Zaman, p. 23)

The mark of the Prophet (saas) is on his shoulder. (Al-Barzanji, Al-Isha'ah li-ashrat al-sa'ah, p. 163)

Our Prophet (saas) has revealed that there will be A SIGN BELONGING TO OUR PROPHET (SAAS) on Hazrat Mahdi’s body. Other hadiths state that THIS SIGN IS THE PROPHET’S SEAL OF PROPHETHOOD and this is compared to the PROPHET’S MARK. This is yet another astonishing detail about Hazrat Mahdi (as).
As we know, THE SEAL IS DARK IN COLOR and COVERS THE SURFACE.
In addition, the location of this mark on Hazrat Mahdi’s (as) back is pinned down by the provision of specific coordinates. Accounts state that every prophet has the seal of prophethood on his right hand. The seal of our Prophet (saas) is described as being “at the level of his heart on the skin of his left shoulder blade.” The reference in the hadiths to Hazrat Mahdi (as) having the seal of prophethood of our Prophet (saas) on his shoulder shows that he will also have “A DARK MARK AT THE LEVEL OF HIS HEART ON HIS BACK, ON HIS LEFT SHOULDER BLADE.”
 
Our Prophet’s (saas) Seal of the Prophethood

Jabir ibn Samurah (ra) relates: “I saw the seal of prophethood between the Messenger of Allah’s (saas) shoulder blades.” (At-Tirmidhi, Imam Abu `Isa Muhammed ibn `Isa Tirmidhi, Shamail Sharif, Vol. 1, Hilal Press, Ankara, 1976, p. 36)

Abu al-Saib bin Yazid relates: "My eye saw the seal of the Prophet (saas) between his shoulders." (Sunan at-Tirmidhi, 6:126)

Ibrahim bin Muhammad, one of the grandsons of Hazrat Ali, relates: “In describing the characteristics of our Prophet (saas), my grandfather Hazrat Ali would relate all the hadith about the physical appearance of the Messenger of Allah (saas) at length and say:

‘There was the seal of prophethood between his shoulder blades. And he is the last of the prophets.’” (At-Tirmidhi, Imam Abu `Isa Muhammed ibn `Isa Tirmidhi, Shamail Sharif, Vol 1. Hilal Press, Ankara, 1976, p. 38)