The Soom Shale is a member of the Late Ordovician (Hirnantian) Cederberg Formation (Table Mountain Group) in South Africa, renowned for its remarkable preservation of soft-tissue in fossil material.

The environment of deposition is considered to be anoxic and occasionally euxinic cold bottom waters, as indicated by the lack of bioturbation and most epibenthic fauna, besides a small amount of transiently colonizing brachiopods during temporary oxic conditions.

It was deposited in the immediate aftermath of the Hirnantian glaciation, the most likely primary cause of the Late Ordovician mass extinction.

The process of preservation for soft tissues is under debate, but possibly could involve replacement by aluminosilicates, but this could just be an artifact of diagenesis and metamorphism.

[6] An incertae sedis bilaterian genus, currently known from a pair of fossils, was discovered in 1998 in the Soom Shale by a team from Leicester University.