The rotten apple is used in the Biohazard and Mourning's Ends Part Iquests. When eaten, the player says "Yuck!" and text in the chat box will appear, stating "It's rotten, you spit it out".
They are found on the ground in north-eastern corner of West Ardougne, in a barrel near the port and several other places on Lunar Isle. South of the Tree Gnome Stronghold there is an orchard containing rotten apples. Players cannot pick rotten apples from the trees, though they may be found on the ground nearby. They may also be found while digging at the Digsite.
They are aesthetically similar to rotten tomatoes, although appear duller in colour and differ slightly in shape.