리틀팍스

From what I read so far, writer said there are 2 posibilities.

One is that it's a monster of colossal strength.

The other one is some type of underwater boat with tremendous engine power.

In my opinion, first idea is nearly impossible. But really seldom, there can be a monster of amazing power. However, it really hardly happens. The example of a monster is like Giant Squid or Giant Octopus, etc. But in the story, the ship named Scotia had been slightly struck, and was found to be in the shape of a triangle. Something punched it but because the shape is triangle, it nearly can't be animal or plants. When they punch something, the figure will be like circle or oval.

So I think there is possible of some kind of underwater boat with tremendous engine power. It doesn't need to be made by nation. It can be made by some scholars or professors who's interested in the sea bottom so that they can explore over the sea. Also someone who doesn't like his or her nation or this world could have made that in treason.

In conclusion, I think it can be some type of underwater ship with great engine power.