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''Horodyskia'' is a 
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
ised organism found in rocks dated from to . Its shape has been described as a "string of beads" connected by a very fine thread. It is considered one of the oldest known eukaryotes.
Biology
Comparisons of different fossils in the same locations suggest that it rearranged itself into fewer but larger main masses as the sediment grew deeper round its base. It may also have had a series of holdfasts along the bottom of the thread. Dimple marks in offshore sandstone have been found in the same deposits as ''Horodyskia'', suggesting that they may be remnants of older holdfasts. Thin sections of ''Horodyskia'' have revealed a system of tubes within the beads, including connecting strings, and other tubes radiating outward from each bead. Partial burial and branching of these tubes suggest that it may have had a benthic sessile lifestyle. Members of the genus are distinguished by bead size and spacing, with the beads of ''H. moniliformi''s being larger and more spaced than ''H. williamsii.''Distribution
Species of ''Horodyskia'' has been found in Western Australia, Southern China, and in parts of North America, They are found in siliciclastic rocks such as sandstone, often as casts or molds.Classification
Like many Precambrian organisms, the biology of ''Horodyskia'' is still poorly understood. As a result, it is difficult to classify what type of organism it may have been. ''Horodyskia'' has been considered an early metazoan, and a colonialforaminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...
n. More recently it has been hypothesized that they are a type of ''Geosiphon
''Geosiphon'' is a genus of fungus in the family Geosiphonaceae. The genus is monotypic, containing the single species ''Geosiphon pyriformis'', first described by Kützing in 1849 as ''Botrydium pyriforme''. In 1915, Von Wettstein characterized ...
''-like fungus
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...
(Glomeromycota
Glomeromycota (often referred to as glomeromycetes, as they include only one class, Glomeromycetes) are one of eight currently recognized divisions within the kingdom Fungi,
with approximately 230 described species. Members of the Glomeromycot ...
, Archaeosporales
Archaeosporales is an order of fungi best known as arbuscular mycorrhiza to vascular land plants (Tracheophyta). But also form free living endocyte symbioses with cyanobacteria. The free living forms have a Precambrian fossil record back 2.2 Ga ...
), due to the similarity of ''Horodyskia’s'' bead-like structures to the bladders of early growth stage ''Geosiphons.''See also
* List of Ediacaran genera *Francevillian biota
The Francevillian biota (also known as Gabon macrofossils or Gabonionta) is a group of 2.1-billion-year-old Palaeoproterozoic, macroscopic organisms known from fossils found in Gabon in the Palaeoproterozoic Francevillian B Formation, a black sha ...
**Francevillian B Formation
The Francevillian B Formation, also known as the Francevillian Formation or FB2 in scientific research, is a geologic formation of black shale provinces close to the town of Franceville, Gabon. The formation was deposited between 2.14-2.08 Ga (b ...
Footnotes
{{Taxonbar, from=Q4040768 Fossils of China Precambrian life Glomeromycota