Diagnosis: Centrohelids lacking silica scales but with numerous thin, pointed organic scales tapering towards acute apices. 18S rRNA short, lacking the seven insertions found in Marophryidae.
Type and sole genus Marophrys.
Diagnosis as for Marophryidae above.
Type species: Marophrys (=Heterophrys) marina comb. nov.
Diagnosis: cell diameter 9 – 45 µm. Spicules radially oriented, numerous, length approximately half the cell diameter, tapering abruptly from base to acute tips.