Alma 46:24 mentions that part of Joseph’s coat survived:
Yea, let us preserve our liberty as a remnant of Joseph; yea, let us remember the words of Jacob, before his death, for behold, he saw that a part of the remnant of the coat of Joseph was preserved and had not decayed. And he said—Even as this remnant of garment of my son hath been preserved, so shall a remnant of the seed of my son be preserved by the hand of God, and be taken unto himself, while the remainder of the seed of Joseph shall perish, even as the remnant of his garment.
This is intriguing because it is not found in the Bible but is found in non-Biblical documents such as the Syriac History of Joseph and the Jewish Book of Jasher. These documents were not translated into English until after the publication of the Book of Mormon so where would Joseph Smith get this idea from?