''Astraeospongium'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

from the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

. Known species include ''A. meniscum'' and ''A. patina''.

Taxonomy

The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of ''Astraeospongium'', ''A. meniscum'', was named by German geologist

Ferdinand von Roemer Carl Ferdinand von Roemer (5 January 1818 – 14 December 1891), German geologist, had originally been educated for the legal profession at Göttingen, but became interested in geology, and abandoning law in 1840, studied science at the Univer ...

in 1848, and was originally assigned to the

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...

n genus '' Blumenbachium''.Roemer F. 1848. Über eine neue Art der Gattung 'Blumenbachium' (König) und mehrere unzweifelhafte Spongien in obersilurischen Kalkschichten der Grafschaft Decatur im Staate Tennessee in Nord-Amerika. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde. 680–686. Stuttgart. In a later publication, Roemer reassigned it to its own genus, ''Astraeospongium'';Roemer, F. 1854. Palaeo-Lethaea, Kohlen-Periode. In: Bronn, H.G. & Rohmer, F. "Lethaea Geognostica". 1 (2): 1–788. Stuttgart. twelve years later, though, he apparently renamed it to ''Astraeospongia meniscus''.Roemer F. 1860. Die silurische Fauna des westlichen Tennessee. Eine palaeontologische Monographie. 100. Eduard Trewendt-Verlag, Breslau. There is no evidence of any argument or intention to change its binomial name, and such a change would be invalid. Thus, ''Astraeospongium meniscum'' is the correct binomial name for the type species. Additional species have been named over the years, including ''A. patina'' and ''A. lancifer''; the latter has been reassigned to '' Gondekia'', which belongs to

Eiffeliidae Eiffeliidae is an extinct family of sponges. Genera The following genera are placed in the family: * †''Astraeoconus'' Rietschel, 1968 * †''Chilcaia'' Carrera, 1994 * †''Eiffelia'' Charles Doolittle Walcott, Walcott, 1920 (synonyms: ''Lena ...

Description

''Astraeospongium'' as a genus is bowl shaped, with a skeleton composed of star-shaped octatin spicules. Most specimens range from though may range from . In ''A. meniscum'', spicules are , though in ''A. patina'', they are only . The youngest spicules are found at the upper surface, particularly close to the rim, and are fairly easily distinguished. About from the base, they begin to recrystalise and are cemented together. In the middle, they fuse into a massive, calcareous basal skeleton that lacks open spaces or channels. It has inferred that soft tissues only occupied the uppermost part of the basal skeleton.

References

{{Taxonbar, from=Q129254925 Calcarea Silurian genera Prehistoric sponge genera Fossil taxa described in 1854 Paleozoic sponges