Ocellus is a noun that refers to the eye of a small creature. 

Our word of the day comes from the Latin word oculus (OH koo loose) which means ‘eye.’ Ocullus has been around since the early 19th century and is always used in reference to the smaller eyes of animals. Here’s an example:

When I saw those tiny worms, I was stunned to learn they had the ability to see. But when Mr. Hammel showed me the creature’s small eyes, I realized that sight was possible for them. True, an ocellus doesn’t always grant an animal a very vivid sense of sight, but for some beings, all they need to survive is the ability to detect differences in light. a