In the 2014 film If I Stay, Chloe Grace Moretz played Mia Hall, a talented cellist caught in a life-changing event after a car accident. 

As part of her character's story, Mia is shown carrying a cello case, symbolizing her passion for music and her connection to her family and life before the accident.

During filming, Chloe Moretz was often seen on set with a cello case, which helped her get into character and served as a reminder of the important role music played in Mia's journey. 

In the movie, Mia's cello is central to her identity and emotional recovery, so the cello case was more than just a prop — it was integral to the storytelling.

The movie, based on Gayle Forman's novel of the same name, explores themes of love, loss, and resilience. 

And Chloe's portrayal of Mia, with the cello always by her side, added depth to the character's emotional and physical struggles as she navigates a difficult path to recovery.