Answer:
The best answer to the question: Why does Wells call the Martian spacecraft "The Thing", would be: Because he still does not know how it is called, but he does know, as he describes it, that after so many years of causing destruction on Earth, it is a machine of terror and desolation.
Explanation:
"The War of The Worlds" is a science fiction novel that was written by author H.G Wells and it was published originally in 1898. The story narrates the events that take place when Earth is invaded by Martians, something that had never even been considered a possibility.
In chapter 1, as the narrator starts to tell us about what is going on, and the author develops the storyline, he starts to tell us how the event of invasion by Martians happened, how initially they were all awed by a planet humans thought uninhabited, or at most, inhabited by inferior beings, and then got the surprise that instead, Mars was filled with beings who, like humans, were plotting how to invade another planet. When he tells us about the arrival, the way that Martians finally arrive on Earth, the narrator uses the word "The Thing", almost in disgust, and shows us that even if the object has been present on Earth for years now, causing destruction and death, he is still unable to name it, or knows how to name it.