The Weirwood Bones of Nagga / Grey King Greenseer Theory - A Song of Ice and Fire - Game of Thrones

Nagga's Bones, thought to be the fossilized ribcage of an ancient sea dragon, are in actuality the petrified weirwood ribbing of the Grey King's ship, which he flipped over and made into a magical longhall. In theory anyway - this is Grey King weirwood ark greenseer theory, at long last.