Haeckel
Fully grown specimens with 4 latticed concentric shells and many (>6) stout, 3-bladed spines (Cromyechinus icosacanthus intro). Outermost shell thin-walled, delicate, with very small, regular, circular pores. Third shell with large, irregular, polygonal pores. Outermost shell diameter without spines: ca. 160 µm.
Ref.: Haeckel (1887).