Per Ahlberg

Sphenothallus, a Palaeozoic genus of uncertain affinity, possibly a hydrozoan, is reported from the Furongian (Cambrian) of Scandinavia. This is the only known occurrence of the genus in Cambrian rocks outside of China, western North America and Bohemia, and also the first report of Sphenothallus in the Cambrian-Ordovician of Baltica. The material is from the upper Furongian (upper Protopeltura and lower Peltura superzones) of Mount Kinnekulle, Vastergotland, south-central Sweden. It consists of elongated, slightly tapering, shiny black phosphatic tubules. Scanning electron microscope photographs confirm paired internal longitudinal thickenings, typical of the genus, on opposite sides of the central lumen. The presence of the Swedish material in a low-energy, dysoxic facies is consistent with most previous occurrences.