Sphaerocoeliidae

Sphaerocoeliidae is an extinct family of calcareous sponges, the only family in the monotypic order Sphaerocoeliida. Sphaerocoeliids are one of several unrelated sponge groups described as "sphinctozoans", with a distinctive multi-chambered body structure. Sphaerocoeliids persisted from the Permian to the Cenomanian stage of the Cretaceous, a longer period of time than most other "sphinctozoans". Sphaerocoeliids make up the majority of calcareous "sphinctozoans", as well as a large portion of post-Triassic "sphinctozoan" diversity. "Sphinctozoans" and the similar "inozoans" were historically grouped together in the polyphyletic order Pharetronida.

In general form, sphaerocoeliids are cylindrical, as a chain of dome-shaped chambers stacked up on each other. Each layer is pierced by a central osculum (outflow vent), which has the form of a simple hole. Sphaerocoeliids are hypermineralized, with a skeleton of loose calcareous spicules cemented together in calcite walls.