Before Dr. Gero was killed by #17, he had entered the design for another android into the
computer. This android was just as smart as Dr. Gero, as Dr. Gero had made him to be just
like himself. This android was referred to as android X, since it was not given a number
before Gero died. This android was a complete weakling but what he lacked in strength he
made up in genius. After the computer had finished creating him he got right to work. He
used the designs of #17 and #18, and the designs of cell to make the ultimate android.