Coronacollina acula
Clites et al., 2012
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Fossils of Coronacollina acula are comprised of a small round boss, with three peripheral raised edges that surround a gently concaved centre. A number of long ridges, interpreted as skeletonised spicules, were attached to the central boss, and radially spread out along the Ediacaran seafloor. Many of these long, thin spicules can be seen preserved on their own, where they may have been torn away from the main body of the organism by prevailing currents or the burial event that preserved them. Some of them can be over 40 cm in length.
Clites et al., (2012) interpret C. acula as an ancient demosponge, comparing it to the Cambrian fossil Choia. Demosponges are the most common sponges living today. Described from: Flinders Ranges, South Australia Key reference: Clites et al., 2012 |
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Diagnosis (from Clites et al., 2012):
Truncated cone 1–22 mm in diameter, 1–15 mm tall associated with narrow (commonly <1 mm wide) straight spicules <2 cm to 37 cm in length, with rare lenticular sections. Multiple spicules (up to four observed) diverge radially from cone and commonly disarticulate. Cone thimble-shaped, with threefold rim (top outer edge) diameter slightly smaller than base diameter. Periphery of cone base not sharply defined. In best-preserved examples, cone symmetrical with circular to polygonal shallow recess at top. Irregular specimens have similar relief and cone shape but lack distinct rims. Spicules attach at cone rim. Smaller specimens have three separate nodes instead of a continuous rim and are not commonly found with associated spicules.
Truncated cone 1–22 mm in diameter, 1–15 mm tall associated with narrow (commonly <1 mm wide) straight spicules <2 cm to 37 cm in length, with rare lenticular sections. Multiple spicules (up to four observed) diverge radially from cone and commonly disarticulate. Cone thimble-shaped, with threefold rim (top outer edge) diameter slightly smaller than base diameter. Periphery of cone base not sharply defined. In best-preserved examples, cone symmetrical with circular to polygonal shallow recess at top. Irregular specimens have similar relief and cone shape but lack distinct rims. Spicules attach at cone rim. Smaller specimens have three separate nodes instead of a continuous rim and are not commonly found with associated spicules.
