D. sacculus is long and oval with a rounded posterior. Width is highly variable with many thin and fat examples found. Occassionally cells have a few blunt spines on the posterior end (Zingone et al. 1998). The thecal surface is very variable ranging from completely smooth to coarsely arelotated. The cell has several smooth pores sparsely/randomly placed anywhere on the cell apart from in the megacytic zone. This species has a highly variable morphology (reviewed in Zingone et al. 1998) which can lead them to being misidentified.