Over 1,500 non-mineralized specimens, representing 50 distinct taxa that have a composition similar to earlier Burgess Shale type biotas, have been recovered from the formations in addition to a less abundant shelly fauna.

[6] The non-mineralized cohort contains a range of forms familiar from the Burgess Shale: Demosponges,[8] lobopods, barnacles, annelids, radiodonts (e.g. Aegirocassis),[9] possible halkieriids, marrellomorphs, paleoscolecid worms, nektaspids, skaniids as well as the expected problematica.

[6] The fossiliferous strata were deposited just above storm wave base (offshore to lower shoreface transition), at between 50 and 150 metres (160 and 490 ft) water depth.

[14][15] Both of these intervals are located near the top of the lower formation, corresponding to the Araneograptus murrayi and Hunnegraptus copiosus graptolite zones respectively.

[1] The Lagerstätten were first identified in the late 1990s when a local fossil collector, Ben Moula, showed some of the finds to a PhD student who was then working in the area.

[22] The largest trilobite individuals in the Fezouata Formation tend to inhabit deep oxygenated waters with minimal influence from storms or larger predators.

These include synziphosurines, xiphosurans (horseshoe crabs), eurypterids, chasmataspidids, phyllocarids, ostracods, a canadaspidid, a leanchoiliid, a cheloniellid (Eoduslia?

[49] Fezouata stylophoran fossils include soft tissue preserved among the skeletal elements, helping to unravel controversial details of their anatomy and ecology.

[50][51] Specific echinoderm species may form dense fossil beds in some layers of the formation, a phenomenon which is particularly common in the mid-late Tremadocian (Araneograptus murrayi graptolite zone).

Cosmopolitan Late Cambrian hallmarks (such as cornute stylophorans) maintain their abundance in oxygen-poor areas, while newer groups (crinoids, diploporites, asterozoans) make inroads into more oxygenated waters.

This also provided more space for the establishment of a distinctive South Polar ecosystem dominated by eocrinoids, mitrates, solutans, and eventually diploporites.

The Fezouata Formation appears to be an exemplar of the 'subpolar domain', an assemblage of cold-water coastal conodonts native to the South Polar region of the Early Ordovician.

[8] Though at least 27 sponge species have been recorded in the biota, nearly all occurrences are monospecific death assemblages, with the exception of Pirania auraeum, which has a broader and less dense distribution in the formation.

Conversely, in Wales there is a clear succession of diverse and sturdy lithistids and thick-walled hexactinellids in shallow reefs and other energetic areas, with protomonaxonids at intermediate depths, and reticulosans in the deepest and calmest environments.