The lost thing is a symbol of interests held during a person's childhood. That's why I thought that everyone else around him didn't notice the thing.
It was lost because at a certain point in life, people start to grow up and start to think logically. In the short film, the boy was always working on his bottle top collection and after he left the lost thing at that odd place, he became an adult and moved on with his life.
What do you guys think?
