Toadbert's Drawing

From the Super Mario Wiki

Toadbert's Drawing is a key item in Mario & Luigi: Partners in Time. It was drawn by Toadbert, who lost his memory, and sketched the memories he still had left. The game description says Toadbert's Odd Drawing. It is drawn very poorly, and has dirt and mud all over it. Mario receives it inside Yoob's Belly in Yoshi's Island.

Later in Star Shrine, Mario had to clean off the mud and dirt using the Stylus, revealing two Princess Shroobs. Just as Toadbert was about to explain, Elder Shrooboid came out of nowhere, and Shroob UFOs turned Toadbert and Kylie Koopa into Shroob Mushrooms. The two princesses were later revealed to be Princess Shroob, and Elder Princess Shroob. The item is never used again, and just remains in the brothers' inventory.