sentence: Compound eyes are different from simple eyes.
sentences_after: Instead of having one organ that can sense light, they put together many such organs. Some compound eyes have thousands of them. The resulting image is put together in the brain, based on the signals of the many eye units. Each such unit is called 'ommatidium', several are called 'ommatidia'. The ommatidia are located on a convex surface, each of them points in a slighly different direction.
concept_name: compound eye
headings: Eye Types of eye Compound eyes
categories: Basic English 850 words