With further investigation, the actual item is 12x35. 35 isn't a multiple of 16 so it would have to use 3 tiles, no one wastes 3 tiles on a detail used once. Upon review of the tile set I didn't see anything that resembled it. AND it doesn't really look like anything... Unless we can rub a magic lamp and say "/showdev"
and a developer appear so we can ask them, I suppose it will be a mystery!