Big Lizard is jealous of the vacuum cleaner and hides it from Dad and Cosima. Ammon decides it's her new best friend, whilst Cosima reassures Big Lizard that he will always be her BFF.

A strange rock far away from the ship breaks D.O.R.I.S.'s satnav. Luckily, Big Lizard's on hand to teach Cosima how to find her way around without technology.

Big Lizard frustrates Dad by stealing a strange plant from the ship. A disaster is averted when Big Lizard persuades Dad that there's more to this plant than meets the eye - and nose...