Consciousness is caused by the arrow of entropy. Any time a chemical or physical process wants to flow towards entropy and is prevented from doing so, it creates a strain that is experienced by the universe. To a bacterium a strain that means "not enough water" is experienced differently from a strain that means "not enough sugar". In the case of neurological animals, certain cells have been given the benefit of experiencing signals rather than their local environments. This has allowed them to craft a meta-being that experiences the world as reported to it be sensor neurons and through internalizing portions of its environment.