Calcareous sponge
| Calcareous sponges Temporal range: Cambrian Series 2 to present | |
|---|---|
| "Calcispongiae" from Ernst Haeckel's Kunstformen der Natur, 1904 | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Porifera |
| Class: | Calcarea Bowerbank, 1864 |
| Subclasses | |
The calcareous sponges (class Calcarea) are members of the animal phylum Porifera, the cellular sponges. They are characterized by spicules made of calcium carbonate, in the form of high-magnesium calcite or aragonite. While the spicules in most species are triradiate (with three points in a single plane), some species may possess two- or four-pointed spicules. Unlike other sponges, calcareans lack microscleres, tiny spicules which reinforce the flesh. In addition, their spicules develop from the outside-in, mineralizing within a hollow organic sheath.
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