What did Otis amber mean by the phrase the turtle has lost it all.?

In the novel "From the Mixed-Up Files of Mrs. Basil E. Frankweiler" by E.L. Konigsburg, Otis Amber's phrase "the turtle has lost it all" symbolizes the idea that the turtle had carried valuable possessions on its back but had lost them in the end, similar to how the characters in the story sought something precious but realized it was within themselves all along. It reflects the theme of self-discovery and the journey of finding one's worth and identity.