Houri are mystical spirits that exist in heaven according to the teachings of Islam. The Houri are described as being modest, beautiful virgins that linger in Paradise. They are hairless, other than on their heads; transparent to the marrow of their bones; and eternally young. They are extremely pure and despite most descriptions being of women, the original Arabic term can refer to a beautiful, pure companion of either gender (which is also referenced in the Qur'an). The Qur'an describes that anyone who enters paradise is promised a beautiful companion of their opposite gender, which refers to the houri. Anyone who enters paradise becomes a youthful houri.