part of ocellar retinula cell ocellus pigment granule VFB:FBbt_00004244 FBbt:00004244 Pigment granule of the photoreceptor cell of the adult ocellus. Pigment granules are found distally around the rim of the ocellus, and proximally down from the level of the nucleus. They are composed of ommatins (brown color pigments) which do not migrate in response to light. fly_anatomy.ontology photoreceptor cell pigment granule