Noun
an eyelike marking (as on the wings of some butterflies); usually a spot of color inside a ring of another color
Source: WordNetBrittle stars, crinoids and sea cucumbers in general do not have sensory organs but some burrowing sea cucumbers of the order Apodida have a single statocyst adjoining each radial nerve and some have an eyespot at the base of each tentacle. Source: Internet
Each of the epitoke segments is packed with eggs and sperm and features a single eyespot on its surface. Source: Internet