develops from develops into ommatidial precursor cluster five-cell ommatidial precursor cluster immature eight-cell ommatidial precursor cluster FBbt:00001772 fly_anatomy.ontology Ommatidial precursor cluster composed of eight future photoreceptors. It forms when the precursors of photoreceptors of R1, R7 and R6 form during the second mitotic wave and join the cluster. The nuclei of these newly joined cells begin to climb apically, with R7 lagging behind R1 and R6. immature eight-cell ommatidial cluster mature eight-cell ommatidial precursor cluster