The Granatoid Tanks is the 26th produced episode and the 20th Broadcast episode of the series Fireball XL5
Dr. Baker and Dr. Simpson have just finished their experiments on the glass- surfaced Planet 73. Suddenly, they discover that six Granatoid tanks (hostile robots) are coming towards the base and they send a message for help to Space City. Aboard Fireball XL5 the crew discover that Ma Doughty, owner of the Space City Music Shop, has stowed away. They reach Planet 73 and when Ma Doughtey appears the tanks retreat. She is wearing perils made from the rare mineral plyton, one only thing the Granatoid tanks fear!