''Monorhaphis'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

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 ...

of siliceous deep sea Hexactinellid

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 ...

s. The single

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

is 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 ...

''Monorhaphis chuni'', a sponge known for creating a single giant basal spicule (G.B.S.) to anchor the sponge in the sediments. The species was described by Franz Eilhard Schulze in 1904 from specimens collected by the German Deep Sea Expedition in 1898–1899. ''Monorhaphis'' is also the only genus in the monotypic family Monorhaphididae. One study provides substantial evidence that an individual of this deep-sea sponge, that forms giant spicules up to 3 meters long, is about 11,000 years old. Five other individuals collected from depths of 1,100 to 2,100 meters at three widely separated locations in the western Pacific Ocean were estimated to be 6,000 to 18,000 (±1,000) years old and grew radially at about 140 μm per 1,000 years. Early growth of the giant spicule is bidirectional, and then unidirectional towards the apex. The samples were shown to record deep ocean silica geochemistry throughout their lives.

References

Hexactinellida Hexactinellida genera Monotypic sponge genera Taxa named by Franz Eilhard Schulze {{sponge-stub