Haeckel
Fully grown specimens with many (up to over 7; 4 in the specimen illustrated) concentric spheres, the innermost with regular hexagonal meshes and cylindrical spines arising from the nodes. At regular distances these spines produce branches which anastomose laterally forming subsequent spheres with a delicate, irregular, cobweb-like network. Branching spines protrude from the surface of the last shell. Diameter of innermost shell: ca. 100 µm.
Ref.: Haeckel (1862).