Currently, there is no scientific evidence to support the existence of ghosts or the ability to perceive them through any form of photoreceptor. Therefore, there is no known extra photoreceptor alternative to cones and rods that can see actual ghosts. Our understanding of vision is primarily based on the functionality of cones and rods, which enable us to perceive light and color. Any claims of additional photoreceptors with the ability to detect supernatural phenomena like ghosts would be purely speculative and not substantiated by scientific research.