The pigment spot ocellus is an
ocellus
A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...
that contains only part of its cells pigmented. It is characteristic of
jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbre ...
,
sea stars, and
flatworms.
["Eye (invertebrate)" McGraw-Hill Encyclopedia of Science & Technology, vol. 6, p.790 2007]
References
Eye
Echinoderm anatomy
Cnidarian anatomy
Protostome anatomy
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