The Squid Plaque is treasure that can be obtained in Sly Cooper: Age of Thieves in the episode Coopers of the Caribbean. It is worth 233 coins and the time needed to reach the safehouse is twenty seconds.
"This ancient plaque once belonged to Henriette's brother, Frederick "One Hand" Cooper, and before his passing, it was his most cherished possession. It's the one thing Clockwerk couldn't steal from him...besides his life..."
It is located at the edge of the harbor. Anyone can bring this treasure to the safehouse.