Haeckel
Two shells and many (>6) primary radial spines. Inner shell with regular polygonal meshes and thin bars. Outer shell with very large, triangular meshes formed by anastomosing of lateral branches produced by the long, 3-bladed primary spines arising from the first shell. Spines extend beyond the very open outer shell. Diameter of inner shell: 150 µm.
Ref.: Haeckel (1887).