Cell (Seru) is the ultimate creation of Doctor Gero. He is an artificial life form created using the cells of several characters from the series, including Goku, Piccolo and Frieza. As a result, Cell is able to perform techniques such as the Kamehameha, a powerful energy blast which he gains from the cells of Goku. In creating the character of Cell, Toriyama tried many different designs before finally settling on the one used in the series. Cell evolves several times throughout his appearances. He originally evolves from a cocoon-like form into his first "Imperfect Form", which is insect-like in appearance. Both his first form and his second "Semi-Perfect Form" have a long tail that ends in a stinger-like appendage and allows it to absorb other organisms. The tail recedes under his wings in his final "Perfect Form", and he can use it to spawn Cell Jr. (Seru Junia), a minuscule child-like version of himself. Requiring the androids #17 and #18 to evolve, he finds out that they are already dead in his timeline, so he kills the Trunks of his timeline and uses Trunks' time machine to travel back in time. He eventually absorbs both after many battles and ascends to his perfect form. He decides to hold the "Cell Games", a tournament in which he fights against the Earth's fighters until there are none left, resulting in Earth's destruction. Cell manages to defeat Goku, but he is eventually killed by Super Saiyan 2 Gohan.