Page "Starfish" Paragraph 21

The eyespots each consist of a mass of ocelli, each consisting of pigmented epithelial cells that respond to light and narrow sensory cells lying between them.

Each ocellus is covered by a thick, transparent cuticle that both protects them and acts as a lens.

Many starfish also possess individual photoreceptor cells across their bodies and are able to respond to light even when their eyespots are covered.