Tyrannosaurus in One Piece

Water 7 Arc

When Mikazuki pestered Paulie at Dock 1, Tyrannosaurus first appeared in his pocket and was later defeated by him, the other carpenters, and his crew. Tyrannosaurus is always seen with Iceburg.

Iceburg claimed to have recently found this mouse and given it the name Tyrannosaurus when he met the Straw Hat Pirates. He asked Kalifa to bring Tyrannosaurus some rodent food and a cage. It stood next to Iceburg's bed the entire while he was recovering from his injuries. Later, when the CP9 set the company's headquarters on fire, instead of fleeing, it attempted to awaken Iceburg but was unsuccessful. It was thankfully saved by Tony Tony Chopper along with his master and Paulie.

Tyrannosaurus was afterward observed laying in Iceburg's pocket as usual during his interview for a new secretary.

From the Decks of the World

Tyrannosaurus is still with Iceburg and his 10-year-old secretary after two years.

From the Decks of the World: The 500,000,000-Man Arc

Tyrannosaurus was in Iceburg's pocket when he and his friends viewed Franky's new wanted poster when it arrived at Water 7.

Tyrannosaurus spends most of its time squealing joyfully whenever Iceburg strokes him while lying in his pocket. It is extremely devoted to and attached to him. Instead of fleeing during the fire at the headquarters of the Galley-La Company, it stayed by its master's side, attempting to wake him with squeaks in order to rescue him.

Tyrannosaurus is a little white mouse with a long, hairless tail, bright red eyes, and a happy expression. It got its name because it usually stands on its hind legs while maintaining a regular mouse position that resembles a Tyrannosaurus Rex in certain ways. Its size has increased dramatically over the past two years, moving from being able to fit in Iceburg's pocket to being roughly the size of its master's head. It is shown wearing a collar and a little suit with vertical stripes.