The cyanophyte Wetheredella in Ordovician reefs and off-reef sediments

Wetheredella tumulus n.sp. was an important constituent, both binder and frame builder, in reef and off-reef sediments of the Ashgillian Ellis Bay Formation of Anticosti Island in eastern Canada. In individual small, stromatolite-like mounds, it built a skeletal platform for attachment of associated serpulid worm tubes, bryozoans, crinoids and small brachiopods. In larger bioherms, Wetheredella was an encruster, binding waveswept reef tops of halysitid and heliolitid corals. Wetheredella is interpreted as a blue-green alga related to Silurian Rothpletzella from Gotland and the genus Girvanella.