Bakker et al. 1982: Globose microfossil, c. 15-22 micron in diameter including the 3-4 micron high massive protuberances rounded at their tips and giving the cell a "fenestrate" appearance.
Bakker R, van Smeerdijk DG (1982) A palaecological study of a Late Holocene section from 'Het Ilperweld', W. Netherlands. Rev. Palaeobot. Palynol. 36:95-163.