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simple eye
simple eye In this historical usage, a simple eye is a very elementary light-sensitive organ, such as an eye-spot or pigment-lined pit, found in many lower animals.
In this historical usage, a simple eye is a very elementary light-sensitive organ, such as an eye-spot or pigment-lined pit, found in many lower animals. It is described as serving basic sensitivity to light, and in pit form it can also provide the structural starting point for more image-forming eyes.