There are no known planets in the universe that continuously change their shape in the sense of undergoing significant, observable transformations over relatively short periods of time. Planets are generally solid bodies that maintain their shape due to gravitational forces and internal structural integrity.
However, it is worth noting that some celestial bodies, such as gas giants like Jupiter and Saturn, have dynamic atmospheres and exhibit various atmospheric features that can change over time. These changes can include the formation and dissipation of storms, the movement and evolution of cloud bands, and other atmospheric phenomena. These transformations occur in the atmosphere of the planet rather than its solid structure.
In addition to planets, there are objects in the universe that exhibit shape-changing behavior. For example, some moons of gas giants, such as Io, experience tidal forces that cause them to flex and deform due to gravitational interactions with their parent planet and other moons. This can result in volcanic activity and surface changes. However, it's important to note that these are moons rather than planets.
So while there are no known planets that continuously change their shape, there are other celestial bodies and objects in the universe that undergo dynamic processes and exhibit various transformations over time.