Phycisphaerae is a class of aquatic bacteria. They reproduce by budding and are found in samples of algae in marine water. Organisms in this group are spherical and have a holdfast, at the tip of a thin cylindrical extension from the cell body called the stalk, at the nonreproductive end that helps them to attach to each other during budding.

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)