Douteki Douteki no Mi (Kinetic Kinetic Fruit) is a Legendary type of Devil Fruit called a Evolutionary Devil Fruit in which the user slowly evolves from One Type of Devil Fruit to Another. In this case this case it allows the user to start out with the Paramecia ability to Manipulate Kinetic Energy in various ways, but it eventually evolves into a Logia which takes the form of the user just constantly in motion(amount can vary) to minimal. Despite being a logia eventually it possesses works more like Phoenix in it's user absorbs kinetic energy to regenerate.
The Devil Fruit came from the Name of the Technology known as Kinetic.
The Devil Fruit was shaped like a Apple-sized Marshmallow