Stylodinium littorale motile cells are oval from the dorsal side. Length 12 - 20 microns, width 9 15 microns. Non-motile cells are a similar shape, surrounded by a hyaline layer, attached to the substrate by a colourless stalk, approximately 15 microns long and 3 microns wide, from the apex. On the motile cell, cingulum begins approximately 0.5 of the cell length from the apex, in the centre of the cell, descending across the dorsal side, not continuing onto the ventral side. Cytoplasm full of small yellow-green plastids. Colourless globules also present. Pyrenoid (2 3 microns) present in the centre of the cell. Nucleus in the hypocone, 3 4 microns wide. Motile cell very fast swimming.
