On paper, she is regarded as the Alchemist's sidekick. But in reality, Mother Pearl is the true mastermind of the crime team. It is her who comes up with their strategies, while her son does all the grunt work.
Mother Pearl helps out her son by making Larry-Boy feel himself down after being sprayed by a special chemical that shrinks others (eg. claiming that Officer Olaf, Herbert and Wally as the true heroes). Even though he finds out their hideout, she and the Alchemist used a machine to create Alter-Ego to defeat the plunger-headed hero.
But that backfired after Larry-Boy becomes humble towards others and ultimately was caught by the police. But not before she gets sprayed by his son's chemical, which after insulting him for being a klutz. Larry-Boy captures her by using his plunger ears to tie her up. Both she and the Alchemist were sent to jail for their crimes.
Mother Pearl is quite cunning, and is considered more calm compare to her son. She likes calling him by his pet name "Cubby", which aggravates him a lot. When dealing with Larry-Boy, she is very manipulative into making him believe that he's superior to everyone else.
Mother Pearl is a white onion with green hair and brown eyebrows. She wears a purple robe over her body and a gold tiara.
- It is weird that Mother Pearl's son is the Alchemist because both characters completely different vegetables (Mother Pearl is an onion, whilst Alchemist is a carrot).
- She is the first Larry-Boy villain to have the most costumes.
- She is also the first villain to be related to another villain.
- There were a few differences that were in the concept art:
- Her cape was going to be black.
- A grey gown with a purple belt was revealed underneath her cape.
- The hair was going to be either brown or purple.
- She may have been a homage to a few characters voice actress June Foray played.
- Her design is similar to Witch Hazel from Looney Tunes, while her voice is reminisces to both Natasha Fatale from "The Rocky and Bullwinkle Show" and Magica De Spell from Disney.