Icy Mammoth Tusk

It is the tusk of a Frozen Mammoth sticking out of an Ice Wall.

One tusk can be can found on Mammoth House's ground floor while other two tusks can be seen on the upper floor of the same house. This object can be moved but not put into your backpack. Because of that the ones on the iceberg can be dragged to houses in Port Hope and even Ankrahmun or Darashia to be used as decoration. There's also a version of it rotated with the tusk pointing east, but it's not present in game anywhere.