van Geel et al (1983b): Globose, hyaline microfossil, 9.8-17.5 µm in diameter, consisting of 7-17 cells varying in diameter from 2.9 µm in the smaller specimens to 6 µm in the largest ones. Walls ca. 0.3 µm thick. Cells at the outer side of the microfossils flattened, showing a characteristic about 0.8 µm raised ring with diameter of 2.4-4.9 µm.
van Geel B, Hallewas DP, Pals JP (1983) A Late Holocene deposit under the Westfriese Zeedijknear Enkhuizen (Prov of Noord-Holland, The Netherlands): palaeoecological and archaeological aspects. Rev. Palaeobot. Palynol. 38:269-335.