Fun fact that ball is (likely) not a solid material. If it's made of rubber or plastic then the base structure is a complex combination of lattice like structures. The water slowly seeps out but it's so slow that the process is invisible to the eye.
Polymers are so rad. I'm always amazed that we discovered such things in the first place and now chemically bond materials to each other. In my field, MEKP or some other catalyst initiates the cross-linking of chains of polymers, usually polyester or vinylester resin unless talking epoxies like with carbon fiber.
I work with composites and this is how fiberglass or carbon fiber parts bind to themselves between the layers. It's fascinating, the chemical reaction basically ties the two surfaces together at the chemical bond level.
