Superfamily SPONGOSPHAEROIDEA Haeckel, 1862

Spongosphaerida Haeckel, 1862: 239, 452 [as a tribe]; 1882: 455 [as a subfamily].

Spongosphaeroidea – Suzuki & Not 2015: 196.

DIAGNOSIS. — Spongy spherical cortical skeleton. Inner part was empty or consisted of a single or double medullary shell. A variable number of three-bladed radial spines, or radial beams, are observed. REMARKS

The Spongosphaeroidea corresponds to the Clade D of Lineage I (Sandin et al. 2021) and includes only the family Spongosphaeridae . Classically, this superfamily includes the Spongosphaeridae and Spongodrymidae; however, the Spongodrymidae was grouped in Clade I of Lineage III (Sandin et al. 2021) and represented by “ Plegmosphaerella ”- form of Plegmosphaeromma (specimen ID Vil210, Vil451 of Sandin et al. 2021). The Spongosphaeridae possess robust three-bladed primary radial beams/spines. In contrast, the Spongodrymidae have fibrous radial beams radiating from the microsphere. Both families have a common centroaxoplastid-type protoplasmic structure of the intracapsular zone, but their central structures are quite different. The Spongosphaeridae have double or single medullary shells (Kurihara & Matsuoka 2004) as a stable character, while the central part of the Spongodrymidae is variable: empty hollow, with a structureless mesh, a fine polyhedron microsphere and other infra-species variations (Hollande & Enjumet 1960; Swanberg et al. 1990).