A compound eye is a type of eye found in many arthropods, such as insects and crustaceans. It consists of thousands of tiny visual units called ommatidia, each contributing to a single image. This structure allows for a wide field of view and the ability to detect motion quickly. Each ommatidium contains its own lens and photoreceptor cells, which capture light and send signals to the brain. Compound eyes are particularly effective in low-light conditions and can perceive ultraviolet light, giving these creatures a unique advantage in their environments.