Picozoa, Picobiliphyta, picobiliphytes, or piliphytes are protists of a phylum of marine unicellular heterotrophic eukaryotes with a size of less than about 3 micrometers. They were formerly treated as eukaryotic algae and the smallest member of photosynthetic picoplankton before it was discovered they do not perform photosynthesis. The phylum currently contains a single species, Picomonas judraskeda. They probably belong in the Archaeplastida as sister of the Rhodophyta.

They were formerly placed within the cryptomonads-haptophytes assemblage.

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