We report a new Middle Ordovician reef-building consortium from North China.
Boundstone consists of bivalve, siliceous sponge, and microbe is found.
Co-occurrence of bivalve and sponge is similar to modern symbiotic analogues.
Bivalve–sponge–microbe association is similar to those in the Mesozoic and Cenozoic.
Diversity of Ordovician reef-building communities was higher than previously thought.