Mub and Grub were looking after the pods for Queen Tara when the Boggans attacked. Being the caretakers, they had to follow Mary Katherine but were captured by Mandrake and forced to look after the pod for him. Eventually, they survived, and made it back to Moon-haven.
Mub is a wise-crack, and throughout the events was trying to chat Mary Katherine up due to the fact he was massively overconfident in himself, thinking that MK liked him, despite the fact that he was a slug, and she was a human. Grub was uptight and in general not a wise-cracker.
Mub has a tense relationship with Nod, because he feels Nod is in the way, and is preventing MK and him from getting together. He frequently tries to insult Nod, calling him, "flat-faced," but usually just comes off as annoying.
- (to Nod about MK): "I saw her first!!"
- (shaking his behind at Nod): "Enjoy the view!!"
- (to Mandrake): "Ugly says what??" (Mandrake asks what he just said) "Nothing......"
- (to Nod): "do you want me to call your flat-faced mommy??"
- Mary Katherine initially mistook Mub to be a snail, whereas it is Grub who is the snail.
- Mub and Grub serve as the comedy relief of the film, having many amusing moments of the sort.
- Mub's actor (Aziz Ansari) ad-libbed a lot of his lines, explaining the random nature of Mub's speech.
- Mub is the only character in the film to attempt to offend Nod, calling him 'flat-face' (He thought of Nod as his love rival). From Mary Katherine's point of view, he is the first non-humanoid character to speak to her directly.
- Mub is one of two characters to fell in love with Mary Katherine, the other one being Nod.