Macnaha qaamuuska ereyga "unugga ololka" waxaa loola jeedaa unug gaar ah oo laga helo habka qashin-qubka ee qaar ka mid ah xididdada laf-dhabarta, sida flatworms (phylum Platyhelminthes) iyo qaar ka mid ah xayawaanka kale ee biyaha. Unugyada ololka waxa kale oo loo yaqaan "protonephridia" waxayna mas'uul ka yihiin inay ka saaraan biyaha xad-dhaafka ah iyo waxyaalaha wasakhda ah ee ku jira jidhka noolaha. loo yaqaan cilia oo ku dhaqaaqa mowjado isku-dubbaridan, oo u eg holac birqaya, sidaas awgeed magaca "unugga ololka." Cilia-yadani waxay abuuraan qulqul ka caawisa inay biyo xad-dhaaf ah iyo wasakhda u soo jiiddo qaab-dhismeed tubbada ah oo loo yaqaan "tubbada unugga ololka," taasoo u horseedda bannaanka jidhka noolaha. osmoregulation, ilaalinta dheelitirka saxda ah ee biyaha iyo solutes gudaha jidhka noolaha. Waa qayb muhiim ah oo ka mid ah nidaamka qashin-saarka ee kuwan laf-dhabarta-la'aanta ah waxayna ka caawiyaan inay habeeyaan deegaankooda gudaha ee degaannada biyaha.