I don't know if you have noticed when watching a movie. In the movie, many plots are that coins fall into the sewer, such as the movie of Xing Ye. In reality, you are afraid of falling into something when you walk through the sewer. It's interesting to think of it now, so I made such a piggy bank. (When I did it, I found that some students in Guangmei had done it, but I still sent it to you. After all, it was very interesting.)