Mermaid's Galloping Extra Episode

Just like the title, a sequel to the Mermaid article The main reason is that I can't stand the 3,000-word chapter. It's too long and too painful, and there is a feeling of uncertainty about the completion. Also, the author of the old post has something to say, the word count of the main text is too frustrating. So I pulled out other extras from the mermaid chapter, such as parallel worlds, past and present lives, and so on, and posted them here.