In Andersen's fairy tale, there is a beautiful and kind-hearted mermaid princess who went through pain and came to the world for the love of her heart, but in the end she failed to stay with her lover as she wished. But her kindness and purity are unforgettable. There are still many things in the world that humans do not know, especially in the depths of the sea. Some of them are beyond the reach of humans, and all we can do is to be in awe; some of them are things that we have forgotten accidentally or intentionally...