The unicellular algae, known as zooxanthellae, or zoox, need to photosynthesise to survive.
Times, Sunday Times (2012)
Moreover, this species consumes filamentous and unicellular algae, diatoms, fungi, and macrophytic remains.
Verónica Williner, Pablo A Collins 2013, 'Feeding ecology of the freshwater crab Trichodactylus borellianus (Decapoda: Trichodactylidae) in the floodplain of the Paraná River, southern South America', Latin American Journal of Aquatic Research
Diatoms are unicellular algae that are used extensively in paleoecology.
Retnaningsih Soeprobowati Tri, Widodo Agung Suedy Sri, Hadiyanto 2018, 'Find the future from the past: Paleolimnology in Indonesia', E3S Web of Conferences