Abstract: An illumination device for insertion entirely inside a typical novelty balloon or the like, said device including: an outer casing having a lower and an upper component and having a substantially spherical or ovoid overall shape, capable of rolling through at least one full revolution on a flat surface; a power source mounted inside said outer casing; and a light generator connected to said power source and mounted inside said outer casing such that light generated by said generator is directed substantially through said upper component; wherein the centre of gravity of said device is located within said lower component of said outer casing.