It is ramose, with a smooth surface and is 3 to 4 cm in extent and up to 6 mm thick.

Approximately a third of the small tetractines have three rows of spines along the distal portion of the apical ray.

The large, regular tetractines are similar to the large triactines with the addition of a shorter, smooth apical ray c. 110 μm long and c. 11.5 μm in diameter at the base.

About 65% of the small tetractines have three rows of spines along the proximal portion of the distal half of the apical ray.

Their length often exceeds the diameter of the adjacent portion of the apical ray.