The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium).

Where is an ommatidium found in the eye of an insect?

Each ommatidium consists of a cornea, which in land insects is curved and acts as a lens. Beneath the cornea is a transparent crystalline cone through which rays converge to an image at the tip of a receptive structure, known as the rhabdom.

Do humans have ommatidium?

However, insect eyes are a little different. As humans have a singular unit for an eye with two eyeballs, insects have what is known as a compound eye where there are many subunits that go into one eye, known as ommatidium. An ommatidium is a singular optical subunit that each has its own lens.