A CA (cellular automata) is a virtual 'smell' that is emitted from agents, such as food and plants, in Creatures Evolution Engine games such as Creatures 3, Creatures Village and Docking Station. Often the agents are invisible so as to give the appearance an area is emitting CAs; for example, an agent in the Grendel Jungle emits Grendel Home Smell, which entices the Grendels to live there. CAs are called "scentons" in the help menu for the smell emitter. They enter through the foot of a creature where the creature contacts the ground, and are detected there, and intepreted by the smell lobe. The reason why creatures smell with their foot touching the ground is to avoid changes which could happen when creatures turn around.[1]