Hexactinellida (Order: Reticulosa)
Diagoniella is placed in the Family Protospongiidae (primitive hexactinellids) and may be confused with Protospongia (Rigby, 1986). Hexactinellid sponges (glass sponges) have a skeleton composed of four to six-pointed siliceous spicules. They are considered to be an early branch within the Porifera phylum due to their distinctive composition.
Diagoniella – from the Greek dia, “throughout, during or across”, and gon, “corner, joint or angle” refering to the diagonal spicules of this sponge.
hindei – for Dr. G. J. Hinde, a British palaeontologist who worked on fossil sponges.
Lectotype –USNM66503 (D. hindei), in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. (D. cyathiformis type and repository information unknown.)
Burgess Shale and vicinity: D. cyathiformis (Dawson, 1889) from the Trilobite Beds and Tulip Beds on Mount Stephen, Walcott Quarry on Fossil Ridge and Stanley Glacier (Caron et al., 2010).
Other deposits: D. coronata Dawson, 1890 from the Ordovician of Québec at Little Métis.
Middle Cambrian, Bathyuriscus-Elrathina Zone to late Middle Cambrian Bolaspidella Assemblage Zone (approximately 505 million years ago).
Burgess Shale and vicinity: This sponge has been found at the Walcott Quarry on Fossil Ridge, the Trilobite Beds and Tulip Beds (S7) localities on Mount Stephen and from Stanley Glacier in Kootenay National Park.
Other deposits: D. cyathiformis (Dawson, 1889) from the Ordovician of Québec at Little Métis to the Middle Cambrian Wheeler and Marjum Formations in Utah (for D. cyathiformis) D. hindei Walcott, 1920 from the Cambrian of Utah and Nevada as well (Rigby, 1978, 1983).
Brief history of research:
Diagoniella was described by Rauff in 1894 as a subgenus of Protospongia. Walcott described a new species, D. hindei, in his 1920 monograph of the sponges from the Burgess Shale and made Diagoniella a valid genus, considering it distinct from Protospongia. Ribgy (1986) restudied the sponges of the Burgess Shale including D. hindei and Rigby and Collins (2004) concluded that another species, known in other Cambrian deposits, D. cyathiformis, is also present in the Burgess Shale.
D. hindei is a small and simple conical sac-like sponge. The skeleton is composed of diagonally orientated coarse spicules along the length of the sponge. These spicules are known as stauracts, and differ from the normal six rayed spicules of the hexactinellid sponges in that they have two rays reduced which gives them a distinctive cross-shape. The spicules knit together to form a net, although, unlike some hexactinellid sponges this net is not fused, which make the sponges very delicate. D. cyathiformis is a larger (up to 120 mm) and more elongate, conical species. The long spicules form a tuft-like root structure at the base of the sponge.
Diagoniella is relatively common but represents only 0.24% of the Walcott Quarry community (Caron and Jackson, 2008).
Diagoniella would have lived attached to the sea floor. Particles of organic matter were extracted from the water as they passed through canals in the sponge’s wall.