The Ancient Clue is a key item that appears in Super Paper Mario.
In Planet Blobule, Squirps needed to go to the bathroom, but someone occupied the bathroom and refused to leave without paper. Mario and company continue their way without Squirps and encountered an active senior explorer, Blappy. He introduced himself to Mario and co.. Blappy has been looking for the "Big Treasure in Space" while other Blobules are searching for snacks. He was willing to sell it to Mario for 1,000 coins, but Mario told him that is "too rich" for his blood. Blappy reduced the cost of 100 coins. Mario agreed to buy it and goes to the bathroom to give the occupier the paper. The occupier was pleased and a Pixl, came out of the toilet named Fleep while Squirps immediately went into the bathroom. Fleep joined Mario's party and Squirps came out of the toilet to continue their journey.
Mario refused to buy the Ancient Clue for 100 coins. Blappy reduced it to 10 coins, Mario refused again thus Blappy insulted Mario saying that it is a business and hates window-shoppers.